* [PATCH v4 0/4] use put_device to cleanup resource
From: weiping zhang @ 2017-12-20 4:26 UTC (permalink / raw)
To: cohuck, mst, jasowang; +Cc: virtualization
Hi,
The main change is split device_register into 2 sperate calls:
device_initalize() and device_add, and then the caller can use
put_device safety when fail to register_virtio_device.
v3->v4:
* split device_register into device_initialize and devicea_add that
the caller can always use put_device when fail to register virtio
device.
v2->v3:
* virtio: add new helper do get device's status then determine use
put_device or kfree.
v1->v2:
* virtio_pci: add comments in commit message for why using put_device
* virtio_vop: also use put_device int _vop_remove_device
weiping zhang (4):
virtio: split device_register into device_initialize and device_add
virtio_pci: don't kfree device on register failure
virtio_vop: don't kfree device on register failure
virtio_remoteproc: don't kfree device on register failure
drivers/misc/mic/vop/vop_main.c | 20 +++++++++++++-------
drivers/remoteproc/remoteproc_virtio.c | 13 +++++++++++--
drivers/virtio/virtio.c | 18 +++++++++++++++---
drivers/virtio/virtio_pci_common.c | 8 ++++++--
4 files changed, 45 insertions(+), 14 deletions(-)
--
2.9.4
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Samudrala, Sridhar @ 2017-12-20 0:26 UTC (permalink / raw)
To: Stephen Hemminger
Cc: mst, netdev, alexander.duyck, virtualization, David Miller
In-Reply-To: <20171219145345.3c261273@xeon-e3>
On 12/19/2017 2:53 PM, Stephen Hemminger wrote:
> On Tue, 19 Dec 2017 14:37:50 -0800
> "Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
>
>> On 12/19/2017 11:46 AM, Stephen Hemminger wrote:
>>> On Tue, 19 Dec 2017 11:42:33 -0800
>>> "Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
>>>
>>>> On 12/19/2017 10:41 AM, Stephen Hemminger wrote:
>>>>> On Tue, 19 Dec 2017 13:21:17 -0500 (EST)
>>>>> David Miller <davem@davemloft.net> wrote:
>>>>>
>>>>>> From: Stephen Hemminger <stephen@networkplumber.org>
>>>>>> Date: Tue, 19 Dec 2017 09:55:48 -0800
>>>>>>
>>>>>>> could be 10ms, just enough to let udev do its renaming
>>>>>> Please, move to some kind of notification or event based handling of
>>>>>> this problem.
>>>>>>
>>>>>> No delay is safe, what if userspace gets swapped out or whatever
>>>>>> else might make userspace stall unexpectedly?
>>>>>>
>>>>> The plan is to remove the delay and do the naming in the kernel.
>>>>> This was suggested by Lennart since udev is only doing naming policy
>>>>> because kernel names were not repeatable.
>>>>>
>>>>> This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly.
>>>>>
>>>>> Patch is pending.
>>>> Do we really need to delay the setup until the name is changed?
>>>> Can't we call dev_set_mtu() and dev_open() until dev_change_name() is done?
>>>>
>>>> Thanks
>>>> Sridhar
>>> You can call dev_set_mtu, but when dev_open is done the device name
>>> can not be changed by userspace.
>> I did a quick test to remove the delay and also the dev_open() call and
>> i don't see
>> any issues with virtio taking over the VF datapath.
>> Only the netdev_info() messages may show old device name.
>>
>> Any specific scenario where we need to explicitly call VF's dev_open()
>> in the VF setup process?
>> I tried i40evf driver loaded after virtio_net AND virtio_net loading
>> after i40evf.
>>
> It happens with hotplug. It is possible on Hyper-V to hotplug SR-IOV on
> and off while guest is running. If SR-IOV is disabled in host then the
> VF device is removed (hotplug) and the inverse. If the master device is
> up then the VF device should be brought up by the master device.
Even with KVM, we need to hot unplug SR-IOV device on the source host
and plug it
back on the destination host to enable live migration. It all works for
me even without
the dev_open() of the lower device from the VF setup routine. Will send
out a v2 version
of this patch without the delayed VF setup after some more testing next
week.
Thanks
Sridhar
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^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Stephen Hemminger @ 2017-12-19 22:53 UTC (permalink / raw)
To: Samudrala, Sridhar
Cc: mst, netdev, alexander.duyck, virtualization, David Miller
In-Reply-To: <ddef3208-3cf5-faa2-7572-a561a6b35e2f@intel.com>
On Tue, 19 Dec 2017 14:37:50 -0800
"Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
> On 12/19/2017 11:46 AM, Stephen Hemminger wrote:
> > On Tue, 19 Dec 2017 11:42:33 -0800
> > "Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
> >
> >> On 12/19/2017 10:41 AM, Stephen Hemminger wrote:
> >>> On Tue, 19 Dec 2017 13:21:17 -0500 (EST)
> >>> David Miller <davem@davemloft.net> wrote:
> >>>
> >>>> From: Stephen Hemminger <stephen@networkplumber.org>
> >>>> Date: Tue, 19 Dec 2017 09:55:48 -0800
> >>>>
> >>>>> could be 10ms, just enough to let udev do its renaming
> >>>> Please, move to some kind of notification or event based handling of
> >>>> this problem.
> >>>>
> >>>> No delay is safe, what if userspace gets swapped out or whatever
> >>>> else might make userspace stall unexpectedly?
> >>>>
> >>> The plan is to remove the delay and do the naming in the kernel.
> >>> This was suggested by Lennart since udev is only doing naming policy
> >>> because kernel names were not repeatable.
> >>>
> >>> This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly.
> >>>
> >>> Patch is pending.
> >> Do we really need to delay the setup until the name is changed?
> >> Can't we call dev_set_mtu() and dev_open() until dev_change_name() is done?
> >>
> >> Thanks
> >> Sridhar
> > You can call dev_set_mtu, but when dev_open is done the device name
> > can not be changed by userspace.
> I did a quick test to remove the delay and also the dev_open() call and
> i don't see
> any issues with virtio taking over the VF datapath.
> Only the netdev_info() messages may show old device name.
>
> Any specific scenario where we need to explicitly call VF's dev_open()
> in the VF setup process?
> I tried i40evf driver loaded after virtio_net AND virtio_net loading
> after i40evf.
>
> Thanks
> Sridhar
It happens with hotplug. It is possible on Hyper-V to hotplug SR-IOV on
and off while guest is running. If SR-IOV is disabled in host then the
VF device is removed (hotplug) and the inverse. If the master device is
up then the VF device should be brought up by the master device.
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^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Samudrala, Sridhar @ 2017-12-19 22:37 UTC (permalink / raw)
To: Stephen Hemminger
Cc: mst, netdev, alexander.duyck, virtualization, David Miller
In-Reply-To: <20171219114627.76dac732@xeon-e3>
On 12/19/2017 11:46 AM, Stephen Hemminger wrote:
> On Tue, 19 Dec 2017 11:42:33 -0800
> "Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
>
>> On 12/19/2017 10:41 AM, Stephen Hemminger wrote:
>>> On Tue, 19 Dec 2017 13:21:17 -0500 (EST)
>>> David Miller <davem@davemloft.net> wrote:
>>>
>>>> From: Stephen Hemminger <stephen@networkplumber.org>
>>>> Date: Tue, 19 Dec 2017 09:55:48 -0800
>>>>
>>>>> could be 10ms, just enough to let udev do its renaming
>>>> Please, move to some kind of notification or event based handling of
>>>> this problem.
>>>>
>>>> No delay is safe, what if userspace gets swapped out or whatever
>>>> else might make userspace stall unexpectedly?
>>>>
>>> The plan is to remove the delay and do the naming in the kernel.
>>> This was suggested by Lennart since udev is only doing naming policy
>>> because kernel names were not repeatable.
>>>
>>> This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly.
>>>
>>> Patch is pending.
>> Do we really need to delay the setup until the name is changed?
>> Can't we call dev_set_mtu() and dev_open() until dev_change_name() is done?
>>
>> Thanks
>> Sridhar
> You can call dev_set_mtu, but when dev_open is done the device name
> can not be changed by userspace.
I did a quick test to remove the delay and also the dev_open() call and
i don't see
any issues with virtio taking over the VF datapath.
Only the netdev_info() messages may show old device name.
Any specific scenario where we need to explicitly call VF's dev_open()
in the VF setup process?
I tried i40evf driver loaded after virtio_net AND virtio_net loading
after i40evf.
Thanks
Sridhar
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Stephen Hemminger @ 2017-12-19 19:46 UTC (permalink / raw)
To: Samudrala, Sridhar
Cc: mst, netdev, alexander.duyck, virtualization, David Miller
In-Reply-To: <344f0afc-b4aa-9f1a-15b8-166ba97d270b@intel.com>
On Tue, 19 Dec 2017 11:42:33 -0800
"Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
> On 12/19/2017 10:41 AM, Stephen Hemminger wrote:
> > On Tue, 19 Dec 2017 13:21:17 -0500 (EST)
> > David Miller <davem@davemloft.net> wrote:
> >
> >> From: Stephen Hemminger <stephen@networkplumber.org>
> >> Date: Tue, 19 Dec 2017 09:55:48 -0800
> >>
> >>> could be 10ms, just enough to let udev do its renaming
> >> Please, move to some kind of notification or event based handling of
> >> this problem.
> >>
> >> No delay is safe, what if userspace gets swapped out or whatever
> >> else might make userspace stall unexpectedly?
> >>
> > The plan is to remove the delay and do the naming in the kernel.
> > This was suggested by Lennart since udev is only doing naming policy
> > because kernel names were not repeatable.
> >
> > This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly.
> >
> > Patch is pending.
> Do we really need to delay the setup until the name is changed?
> Can't we call dev_set_mtu() and dev_open() until dev_change_name() is done?
>
> Thanks
> Sridhar
You can call dev_set_mtu, but when dev_open is done the device name
can not be changed by userspace.
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Samudrala, Sridhar @ 2017-12-19 19:42 UTC (permalink / raw)
To: Stephen Hemminger, David Miller
Cc: netdev, virtualization, alexander.duyck, mst
In-Reply-To: <20171219104159.30d9caaf@xeon-e3>
On 12/19/2017 10:41 AM, Stephen Hemminger wrote:
> On Tue, 19 Dec 2017 13:21:17 -0500 (EST)
> David Miller <davem@davemloft.net> wrote:
>
>> From: Stephen Hemminger <stephen@networkplumber.org>
>> Date: Tue, 19 Dec 2017 09:55:48 -0800
>>
>>> could be 10ms, just enough to let udev do its renaming
>> Please, move to some kind of notification or event based handling of
>> this problem.
>>
>> No delay is safe, what if userspace gets swapped out or whatever
>> else might make userspace stall unexpectedly?
>>
> The plan is to remove the delay and do the naming in the kernel.
> This was suggested by Lennart since udev is only doing naming policy
> because kernel names were not repeatable.
>
> This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly.
>
> Patch is pending.
Do we really need to delay the setup until the name is changed?
Can't we call dev_set_mtu() and dev_open() until dev_change_name() is done?
Thanks
Sridhar
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Stephen Hemminger @ 2017-12-19 18:41 UTC (permalink / raw)
To: David Miller
Cc: mst, sridhar.samudrala, alexander.duyck, virtualization, netdev
In-Reply-To: <20171219.132117.666798483874609477.davem@davemloft.net>
On Tue, 19 Dec 2017 13:21:17 -0500 (EST)
David Miller <davem@davemloft.net> wrote:
> From: Stephen Hemminger <stephen@networkplumber.org>
> Date: Tue, 19 Dec 2017 09:55:48 -0800
>
> > could be 10ms, just enough to let udev do its renaming
>
> Please, move to some kind of notification or event based handling of
> this problem.
>
> No delay is safe, what if userspace gets swapped out or whatever
> else might make userspace stall unexpectedly?
>
The plan is to remove the delay and do the naming in the kernel.
This was suggested by Lennart since udev is only doing naming policy
because kernel names were not repeatable.
This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly.
Patch is pending.
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: David Miller @ 2017-12-19 18:21 UTC (permalink / raw)
To: stephen; +Cc: mst, sridhar.samudrala, alexander.duyck, virtualization, netdev
In-Reply-To: <20171219095548.61d70d10@xeon-e3>
From: Stephen Hemminger <stephen@networkplumber.org>
Date: Tue, 19 Dec 2017 09:55:48 -0800
> could be 10ms, just enough to let udev do its renaming
Please, move to some kind of notification or event based handling of
this problem.
No delay is safe, what if userspace gets swapped out or whatever
else might make userspace stall unexpectedly?
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: David Miller @ 2017-12-19 18:20 UTC (permalink / raw)
To: sridhar.samudrala; +Cc: mst, netdev, alexander.duyck, virtualization
In-Reply-To: <ca709329-a47a-2e76-b1fc-38fc665d7c0b@intel.com>
From: "Samudrala, Sridhar" <sridhar.samudrala@intel.com>
Date: Tue, 19 Dec 2017 09:41:39 -0800
> This is based on netvsc implementation and here is the commit that
> added this delay. Not sure if this needs to be 100ms.
>
> commit 6123c66854c174e4982f98195100c1d990f9e5e6
> Author: stephen hemminger <stephen@networkplumber.org>
> Date: Wed Aug 9 17:46:03 2017 -0700
>
> netvsc: delay setup of VF device
>
> When VF device is discovered, delay bring it automatically up in
> order to allow userspace to some simple changes (like renaming).
This is kind of bogus, I should have called this out when the patch
was posted.
Any delay is wrong, there needs to be tight synchronization if a
userspace operation must occur before proceeding. If something
happens and userspace is delayed, this whole thing doesn't work.
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Stephen Hemminger @ 2017-12-19 18:13 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: Samudrala, Sridhar, virtualization, alexander.duyck, netdev
In-Reply-To: <20171219200611-mutt-send-email-mst@kernel.org>
On Tue, 19 Dec 2017 20:07:01 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Tue, Dec 19, 2017 at 09:55:48AM -0800, Stephen Hemminger wrote:
> > On Tue, 19 Dec 2017 09:41:39 -0800
> > "Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
> >
> > > On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:
> > > > I'll need to look at this more, in particular the feature
> > > > bit is missing here. For now one question:
> > > >
> > > > On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:
> > > >> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
> > > >> */
> > > >> DECLARE_EWMA(pkt_len, 0, 64)
> > > >>
> > > >> +#define VF_TAKEOVER_INT (HZ / 10)
> > > >> +
> > > >> #define VIRTNET_DRIVER_VERSION "1.0.0"
> > > >>
> > > >> static const unsigned long guest_offloads[] = {
> > > > Why is this delay necessary? And why by 100ms?
> > >
> > > This is based on netvsc implementation and here is the commit that
> > > added this delay. Not sure if this needs to be 100ms.
> > >
> > > commit 6123c66854c174e4982f98195100c1d990f9e5e6
> > > Author: stephen hemminger <stephen@networkplumber.org>
> > > Date: Wed Aug 9 17:46:03 2017 -0700
> > >
> > > netvsc: delay setup of VF device
> > >
> > > When VF device is discovered, delay bring it automatically up in
> > > order to allow userspace to some simple changes (like renaming).
> > >
> > >
> > >
> >
> > could be 10ms, just enough to let udev do its renaming
>
> Isn't there a way not to depend on udev completing its thing within a given timeframe?
Not that I know. the path is quite indirect.
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^ permalink raw reply
* Re: [PATCH v20 0/7] Virtio-balloon Enhancement
From: Michael S. Tsirkin @ 2017-12-19 18:08 UTC (permalink / raw)
To: Tetsuo Handa
Cc: yang.zhang.wz, kvm, liliang.opensource, qemu-devel,
virtualization, linux-mm, aarcange, virtio-dev, mawilcox, willy,
nilal, riel, cornelia.huck, mhocko, quan.xu0, linux-kernel,
amit.shah, pbonzini, akpm, mgorman
In-Reply-To: <201712192305.AAE21882.MtQHJOFFSFVOLO@I-love.SAKURA.ne.jp>
On Tue, Dec 19, 2017 at 11:05:11PM +0900, Tetsuo Handa wrote:
> Wei Wang wrote:
> > ChangeLog:
> > v19->v20:
> > 1) patch 1: xbitmap
> > - add __rcu to "void **slot";
> > - remove the exceptional path.
> > 2) patch 3: xbitmap
> > - DeveloperNotes: add an item to comment that the current bit range
> > related APIs operating on extremely large ranges (e.g.
> > [0, ULONG_MAX)) will take too long time. This can be optimized in
> > the future.
> > - remove the exceptional path;
> > - remove xb_preload_and_set();
> > - reimplement xb_clear_bit_range to make its usage close to
> > bitmap_clear;
> > - rename xb_find_next_set_bit to xb_find_set, and re-implement it
> > in a style close to find_next_bit;
> > - rename xb_find_next_zero_bit to xb_find_clear, and re-implement
> > it in a stytle close to find_next_zero_bit;
> > - separate the implementation of xb_find_set and xb_find_clear for
> > the convenience of future updates.
>
> Removing exceptional path made this patch easier to read.
> But what I meant is
>
> Can you eliminate exception path and fold all xbitmap patches into one, and
> post only one xbitmap patch without virtio-balloon changes?
And then people will complain that patch is too big
and hard to understand without any users.
As long as patches don't change the same lines of code,
it's fine to split up imho. In this case it's done
to attribute code better, seems like a reasonable thing to do
to me.
> .
>
> I still think we don't need xb_preload()/xb_preload_end().
> I think xb_find_set() has a bug in !node path.
>
> Also, please avoid unconditionally adding to builtin modules.
> There are users who want to save even few KB.
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Michael S. Tsirkin @ 2017-12-19 18:07 UTC (permalink / raw)
To: Stephen Hemminger
Cc: Samudrala, Sridhar, virtualization, alexander.duyck, netdev
In-Reply-To: <20171219095548.61d70d10@xeon-e3>
On Tue, Dec 19, 2017 at 09:55:48AM -0800, Stephen Hemminger wrote:
> On Tue, 19 Dec 2017 09:41:39 -0800
> "Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
>
> > On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:
> > > I'll need to look at this more, in particular the feature
> > > bit is missing here. For now one question:
> > >
> > > On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:
> > >> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
> > >> */
> > >> DECLARE_EWMA(pkt_len, 0, 64)
> > >>
> > >> +#define VF_TAKEOVER_INT (HZ / 10)
> > >> +
> > >> #define VIRTNET_DRIVER_VERSION "1.0.0"
> > >>
> > >> static const unsigned long guest_offloads[] = {
> > > Why is this delay necessary? And why by 100ms?
> >
> > This is based on netvsc implementation and here is the commit that
> > added this delay. Not sure if this needs to be 100ms.
> >
> > commit 6123c66854c174e4982f98195100c1d990f9e5e6
> > Author: stephen hemminger <stephen@networkplumber.org>
> > Date: Wed Aug 9 17:46:03 2017 -0700
> >
> > netvsc: delay setup of VF device
> >
> > When VF device is discovered, delay bring it automatically up in
> > order to allow userspace to some simple changes (like renaming).
> >
> >
> >
>
> could be 10ms, just enough to let udev do its renaming
Isn't there a way not to depend on udev completing its thing within a given timeframe?
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Stephen Hemminger @ 2017-12-19 17:55 UTC (permalink / raw)
To: Samudrala, Sridhar
Cc: netdev, virtualization, alexander.duyck, Michael S. Tsirkin
In-Reply-To: <ca709329-a47a-2e76-b1fc-38fc665d7c0b@intel.com>
On Tue, 19 Dec 2017 09:41:39 -0800
"Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:
> On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:
> > I'll need to look at this more, in particular the feature
> > bit is missing here. For now one question:
> >
> > On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:
> >> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
> >> */
> >> DECLARE_EWMA(pkt_len, 0, 64)
> >>
> >> +#define VF_TAKEOVER_INT (HZ / 10)
> >> +
> >> #define VIRTNET_DRIVER_VERSION "1.0.0"
> >>
> >> static const unsigned long guest_offloads[] = {
> > Why is this delay necessary? And why by 100ms?
>
> This is based on netvsc implementation and here is the commit that
> added this delay. Not sure if this needs to be 100ms.
>
> commit 6123c66854c174e4982f98195100c1d990f9e5e6
> Author: stephen hemminger <stephen@networkplumber.org>
> Date: Wed Aug 9 17:46:03 2017 -0700
>
> netvsc: delay setup of VF device
>
> When VF device is discovered, delay bring it automatically up in
> order to allow userspace to some simple changes (like renaming).
>
>
>
could be 10ms, just enough to let udev do its renaming
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^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Samudrala, Sridhar @ 2017-12-19 17:41 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: netdev, alexander.duyck, virtualization
In-Reply-To: <20171219174259-mutt-send-email-mst@kernel.org>
On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:
> I'll need to look at this more, in particular the feature
> bit is missing here. For now one question:
>
> On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:
>> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
>> */
>> DECLARE_EWMA(pkt_len, 0, 64)
>>
>> +#define VF_TAKEOVER_INT (HZ / 10)
>> +
>> #define VIRTNET_DRIVER_VERSION "1.0.0"
>>
>> static const unsigned long guest_offloads[] = {
> Why is this delay necessary? And why by 100ms?
This is based on netvsc implementation and here is the commit that
added this delay. Not sure if this needs to be 100ms.
commit 6123c66854c174e4982f98195100c1d990f9e5e6
Author: stephen hemminger <stephen@networkplumber.org>
Date: Wed Aug 9 17:46:03 2017 -0700
netvsc: delay setup of VF device
When VF device is discovered, delay bring it automatically up in
order to allow userspace to some simple changes (like renaming).
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply
* Re: [PATCH v20 1/7] xbitmap: Introduce xbitmap
From: Philippe Ombredanne @ 2017-12-19 15:58 UTC (permalink / raw)
To: mawilcox
Cc: yang.zhang.wz, kvm, mst, penguin-kernel, liliang.opensource,
qemu-devel, virtualization, linux-mm, aarcange, virtio-dev, willy,
nilal, riel, cornelia.huck, mhocko, quan.xu0, LKML, amit.shah,
Paolo Bonzini, Andrew Morton, mgorman
In-Reply-To: <1513685879-21823-2-git-send-email-wei.w.wang@intel.com>
Matthew,
On Tue, Dec 19, 2017 at 1:17 PM, Wei Wang <wei.w.wang@intel.com> wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> The eXtensible Bitmap is a sparse bitmap representation which is
> efficient for set bits which tend to cluster. It supports up to
> 'unsigned long' worth of bits, and this commit adds the bare bones --
> xb_set_bit(), xb_clear_bit() and xb_test_bit().
<snip>
> --- /dev/null
> +++ b/include/linux/xbitmap.h
> @@ -0,0 +1,49 @@
> +/*
> + * eXtensible Bitmaps
> + * Copyright (c) 2017 Microsoft Corporation <mawilcox@microsoft.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of the
> + * License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * eXtensible Bitmaps provide an unlimited-size sparse bitmap facility.
> + * All bits are initially zero.
> + */
Would you mind using the new SPDX tags documented in Thomas patch set
[1] rather than this fine but longer legalese?
And if you could spread the word to others in your team this would be very nice.
Thank you!
[1] https://lkml.org/lkml/2017/12/4/934
--
Cordially
Philippe Ombredanne
^ permalink raw reply
* Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
From: Michael S. Tsirkin @ 2017-12-19 15:47 UTC (permalink / raw)
To: Sridhar Samudrala; +Cc: netdev, alexander.duyck, virtualization
In-Reply-To: <1513644036-45230-1-git-send-email-sridhar.samudrala@intel.com>
I'll need to look at this more, in particular the feature
bit is missing here. For now one question:
On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:
> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
> */
> DECLARE_EWMA(pkt_len, 0, 64)
>
> +#define VF_TAKEOVER_INT (HZ / 10)
> +
> #define VIRTNET_DRIVER_VERSION "1.0.0"
>
> static const unsigned long guest_offloads[] = {
Why is this delay necessary? And why by 100ms?
^ permalink raw reply
* Re: [PATCH v3 5/5] virtio: add comments for virtio_register_device
From: weiping zhang @ 2017-12-19 15:23 UTC (permalink / raw)
To: Cornelia Huck; +Cc: virtualization, Michael S . Tsirkin
In-Reply-To: <20171219121159.17b8c060.cohuck@redhat.com>
2017-12-19 19:11 GMT+08:00 Cornelia Huck <cohuck@redhat.com>:
> On Sun, 17 Dec 2017 21:48:05 +0800
> weiping zhang <zwp10758@gmail.com> wrote:
>
>> As mentioned at drivers/base/core.c:
>> /*
>> * NOTE: _Never_ directly free @dev after calling this function, even
>> * if it returned an error! Always use put_device() to give up the
>> * reference initialized in this function instead.
>> */
>> virtio_register_device may fail before/after call device_register, the
>> caller should do a proper cleanup. Caller cann't use kfree directly,
>> if virtio_register_device has already called device_register. Caller
>> cann't use put_device directly, if virtio_register_device has not yet
>> call device_register, because kobject_put may give a warning cause
>> dev->kobj has not been initialized.
>
> This comment makes me inclined to think that we should also rethink
> register_virtio_device(). On failure, we cannot do kfree() due to
> driver core interaction; but we cannot do a put_device() either, since
> the refcount may not yet have been initialized -- unless we check the
> device status, which triggers I/O (at least on s390).
>
> We really want to do the same cleanup on error in every case. What
> about splitting device_register() into device_initialize() and
> device_add()? If we move device_initialize() before getting an index,
> we should be fine with doing put_device() on error in every case.
>
Good idea (^_^), I''ll apply it at V4.
^ permalink raw reply
* Re: [PATCH v20 0/7] Virtio-balloon Enhancement
From: Matthew Wilcox @ 2017-12-19 14:40 UTC (permalink / raw)
To: Tetsuo Handa
Cc: yang.zhang.wz, kvm, mst, liliang.opensource, qemu-devel,
virtualization, linux-mm, aarcange, virtio-dev, mawilcox, nilal,
riel, cornelia.huck, mhocko, quan.xu0, linux-kernel, amit.shah,
pbonzini, akpm, mgorman
In-Reply-To: <201712192305.AAE21882.MtQHJOFFSFVOLO@I-love.SAKURA.ne.jp>
On Tue, Dec 19, 2017 at 11:05:11PM +0900, Tetsuo Handa wrote:
> Removing exceptional path made this patch easier to read.
> But what I meant is
>
> Can you eliminate exception path and fold all xbitmap patches into one, and
> post only one xbitmap patch without virtio-balloon changes?
>
> .
>
> I still think we don't need xb_preload()/xb_preload_end().
> I think xb_find_set() has a bug in !node path.
Don't think. Write a test-case. Please. If it shows a bug, then great,
Wei has an example of what the bug is to fix. If it doesn't show a bug,
then we can add it to the test suite anyway, to ensure that case continues
to work in the future.
> Also, please avoid unconditionally adding to builtin modules.
> There are users who want to save even few KB.
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply
* [PATCH v20 7/7] virtio-balloon: don't report free pages when page poisoning is enabled
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
The guest free pages should not be discarded by the live migration thread
when page poisoning is enabled with PAGE_POISONING_NO_SANITY=n, because
skipping the transfer of such poisoned free pages will trigger false
positive when new pages are allocated and checked on the destination.
This patch adds a config field, poison_val. Guest writes to the config
field to tell the host about the poisoning value. The value will be 0 in
the following cases:
1) PAGE_POISONING_NO_SANITY is enabled;
2) page poisoning is disabled; or
3) PAGE_POISONING_ZERO is enabled.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
---
drivers/virtio/virtio_balloon.c | 8 ++++++++
include/uapi/linux/virtio_balloon.h | 2 ++
2 files changed, 10 insertions(+)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index eae65c1..1fa8598 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -860,6 +860,7 @@ static struct file_system_type balloon_fs = {
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
+ __u32 poison_val;
int err;
if (!vdev->config->get) {
@@ -897,6 +898,13 @@ static int virtballoon_probe(struct virtio_device *vdev)
WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
INIT_WORK(&vb->report_free_page_work, report_free_page);
vb->stop_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID;
+ if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
+ !page_poisoning_enabled())
+ poison_val = 0;
+ else
+ poison_val = PAGE_POISON;
+ virtio_cwrite(vb->vdev, struct virtio_balloon_config,
+ poison_val, &poison_val);
}
vb->nb.notifier_call = virtballoon_oom_notify;
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 58f1274..f270e9e 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -48,6 +48,8 @@ struct virtio_balloon_config {
__u32 actual;
/* Free page report command id, readonly by guest */
__u32 free_page_report_cmd_id;
+ /* Stores PAGE_POISON if page poisoning with sanity check is in use */
+ __u32 poison_val;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
--
2.7.4
^ permalink raw reply related
* [PATCH v20 6/7] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
Negotiation of the VIRTIO_BALLOON_F_FREE_PAGE_VQ feature indicates the
support of reporting hints of guest free pages to host via virtio-balloon.
Host requests the guest to report free pages by sending a new cmd
id to the guest via the free_page_report_cmd_id configuration register.
When the guest starts to report, the first element added to the free page
vq is the cmd id given by host. When the guest finishes the reporting
of all the free pages, VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID is added
to the vq to tell host that the reporting is done. Host may also requests
the guest to stop the reporting in advance by sending the stop cmd id to
the guest via the configuration register.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
---
drivers/virtio/virtio_balloon.c | 202 ++++++++++++++++++++++++++++++------
include/uapi/linux/virtio_balloon.h | 4 +
2 files changed, 174 insertions(+), 32 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index fff0a3f..eae65c1 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -55,7 +55,12 @@ static struct vfsmount *balloon_mnt;
struct virtio_balloon {
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
+
+ /* Balloon's own wq for cpu-intensive work items */
+ struct workqueue_struct *balloon_wq;
+ /* The free page reporting work item submitted to the balloon wq */
+ struct work_struct report_free_page_work;
/* The balloon servicing is delegated to a freezable workqueue. */
struct work_struct update_balloon_stats_work;
@@ -65,6 +70,13 @@ struct virtio_balloon {
spinlock_t stop_update_lock;
bool stop_update;
+ /* Start to report free pages */
+ bool report_free_page;
+ /* Stores the cmd id given by host to start the free page reporting */
+ uint32_t start_cmd_id;
+ /* Stores STOP_ID as a sign to tell host that the reporting is done */
+ uint32_t stop_cmd_id;
+
/* Waiting for host to ack the pages we released. */
wait_queue_head_t acked;
@@ -189,6 +201,28 @@ static void batch_balloon_page_sg(struct virtio_balloon *vb,
kick_and_wait(vq, vb->acked);
}
+static void batch_free_page_sg(struct virtqueue *vq,
+ unsigned long pfn,
+ uint32_t len)
+{
+ add_one_sg(vq, pfn, len);
+
+ /* Batch till the vq is full */
+ if (!vq->num_free)
+ virtqueue_kick(vq);
+}
+
+static void send_cmd_id(struct virtio_balloon *vb, void *addr)
+{
+ struct scatterlist sg;
+ int err;
+
+ sg_init_one(&sg, addr, sizeof(uint32_t));
+ err = virtqueue_add_outbuf(vb->free_page_vq, &sg, 1, vb, GFP_KERNEL);
+ BUG_ON(err);
+ virtqueue_kick(vb->free_page_vq);
+}
+
/*
* Send balloon pages in sgs to host. The balloon pages are recorded in the
* page xbitmap. Each bit in the bitmap corresponds to a page of PAGE_SIZE.
@@ -498,17 +532,6 @@ static void stats_handle_request(struct virtio_balloon *vb)
virtqueue_kick(vq);
}
-static void virtballoon_changed(struct virtio_device *vdev)
-{
- struct virtio_balloon *vb = vdev->priv;
- unsigned long flags;
-
- spin_lock_irqsave(&vb->stop_update_lock, flags);
- if (!vb->stop_update)
- queue_work(system_freezable_wq, &vb->update_balloon_size_work);
- spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-}
-
static inline s64 towards_target(struct virtio_balloon *vb)
{
s64 target;
@@ -525,6 +548,36 @@ static inline s64 towards_target(struct virtio_balloon *vb)
return target - vb->num_pages;
}
+static void virtballoon_changed(struct virtio_device *vdev)
+{
+ struct virtio_balloon *vb = vdev->priv;
+ unsigned long flags;
+ __u32 cmd_id;
+ s64 diff = towards_target(vb);
+
+ if (diff) {
+ spin_lock_irqsave(&vb->stop_update_lock, flags);
+ if (!vb->stop_update)
+ queue_work(system_freezable_wq,
+ &vb->update_balloon_size_work);
+ spin_unlock_irqrestore(&vb->stop_update_lock, flags);
+ }
+
+ virtio_cread(vb->vdev, struct virtio_balloon_config,
+ free_page_report_cmd_id, &cmd_id);
+ if (cmd_id == VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID) {
+ WRITE_ONCE(vb->report_free_page, false);
+ } else if (cmd_id != vb->start_cmd_id) {
+ /*
+ * Host requests to start the reporting by sending a new cmd
+ * id.
+ */
+ WRITE_ONCE(vb->report_free_page, true);
+ vb->start_cmd_id = cmd_id;
+ queue_work(vb->balloon_wq, &vb->report_free_page_work);
+ }
+}
+
static void update_balloon_size(struct virtio_balloon *vb)
{
u32 actual = vb->num_pages;
@@ -602,40 +655,116 @@ static void update_balloon_size_func(struct work_struct *work)
static int init_vqs(struct virtio_balloon *vb)
{
- struct virtqueue *vqs[3];
- vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
- static const char * const names[] = { "inflate", "deflate", "stats" };
- int err, nvqs;
+ struct virtqueue **vqs;
+ vq_callback_t **callbacks;
+ const char **names;
+ struct scatterlist sg;
+ int i, nvqs, err = -ENOMEM;
+
+ /* Inflateq and deflateq are used unconditionally */
+ nvqs = 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ))
+ nvqs++;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ))
+ nvqs++;
+
+ /* Allocate space for find_vqs parameters */
+ vqs = kcalloc(nvqs, sizeof(*vqs), GFP_KERNEL);
+ if (!vqs)
+ goto err_vq;
+ callbacks = kmalloc_array(nvqs, sizeof(*callbacks), GFP_KERNEL);
+ if (!callbacks)
+ goto err_callback;
+ names = kmalloc_array(nvqs, sizeof(*names), GFP_KERNEL);
+ if (!names)
+ goto err_names;
+
+ callbacks[0] = balloon_ack;
+ names[0] = "inflate";
+ callbacks[1] = balloon_ack;
+ names[1] = "deflate";
+
+ i = 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+ callbacks[i] = stats_request;
+ names[i] = "stats";
+ i++;
+ }
- /*
- * We expect two virtqueues: inflate and deflate, and
- * optionally stat.
- */
- nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
- err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL);
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ)) {
+ callbacks[i] = NULL;
+ names[i] = "free_page_vq";
+ }
+
+ err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names,
+ NULL, NULL);
if (err)
- return err;
+ goto err_find;
vb->inflate_vq = vqs[0];
vb->deflate_vq = vqs[1];
+ i = 2;
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
- struct scatterlist sg;
- unsigned int num_stats;
- vb->stats_vq = vqs[2];
-
+ vb->stats_vq = vqs[i++];
/*
* Prime this virtqueue with one buffer so the hypervisor can
* use it to signal us later (it can't be broken yet!).
*/
- num_stats = update_balloon_stats(vb);
-
- sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
+ sg_init_one(&sg, vb->stats, sizeof(vb->stats));
if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
- < 0)
- BUG();
+ < 0) {
+ dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
+ __func__);
+ goto err_find;
+ }
virtqueue_kick(vb->stats_vq);
}
+
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ))
+ vb->free_page_vq = vqs[i];
+
+ kfree(names);
+ kfree(callbacks);
+ kfree(vqs);
return 0;
+
+err_find:
+ kfree(names);
+err_names:
+ kfree(callbacks);
+err_callback:
+ kfree(vqs);
+err_vq:
+ return err;
+}
+
+static bool virtio_balloon_send_free_pages(void *opaque, unsigned long pfn,
+ unsigned long nr_pages)
+{
+ struct virtio_balloon *vb = (struct virtio_balloon *)opaque;
+ uint32_t len = nr_pages << PAGE_SHIFT;
+
+ if (!READ_ONCE(vb->report_free_page))
+ return false;
+
+ batch_free_page_sg(vb->free_page_vq, pfn, len);
+
+ return true;
+}
+
+static void report_free_page(struct work_struct *work)
+{
+ struct virtio_balloon *vb;
+
+ vb = container_of(work, struct virtio_balloon, report_free_page_work);
+ /* Start by sending the obtained cmd id to the host with an outbuf */
+ send_cmd_id(vb, &vb->start_cmd_id);
+ walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
+ /*
+ * End by sending the stop id to the host with an outbuf. Use the
+ * non-batching mode here to trigger a kick after adding the stop id.
+ */
+ send_cmd_id(vb, &vb->stop_cmd_id);
}
#ifdef CONFIG_BALLOON_COMPACTION
@@ -763,6 +892,13 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_SG))
xb_init(&vb->page_xb);
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ)) {
+ vb->balloon_wq = alloc_workqueue("balloon-wq",
+ WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
+ INIT_WORK(&vb->report_free_page_work, report_free_page);
+ vb->stop_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID;
+ }
+
vb->nb.notifier_call = virtballoon_oom_notify;
vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
err = register_oom_notifier(&vb->nb);
@@ -827,6 +963,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
spin_unlock_irq(&vb->stop_update_lock);
cancel_work_sync(&vb->update_balloon_size_work);
cancel_work_sync(&vb->update_balloon_stats_work);
+ cancel_work_sync(&vb->report_free_page_work);
remove_common(vb);
#ifdef CONFIG_BALLOON_COMPACTION
@@ -880,6 +1017,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
VIRTIO_BALLOON_F_SG,
+ VIRTIO_BALLOON_F_FREE_PAGE_VQ,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 37780a7..58f1274 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -35,15 +35,19 @@
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
#define VIRTIO_BALLOON_F_SG 3 /* Use sg instead of PFN lists */
+#define VIRTIO_BALLOON_F_FREE_PAGE_VQ 4 /* VQ to report free pages */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
+#define VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID 0
struct virtio_balloon_config {
/* Number of pages host wants Guest to give up. */
__u32 num_pages;
/* Number of pages we've actually got in balloon. */
__u32 actual;
+ /* Free page report command id, readonly by guest */
+ __u32 free_page_report_cmd_id;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
--
2.7.4
^ permalink raw reply related
* [PATCH v20 5/7] mm: support reporting free page blocks
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
This patch adds support to walk through the free page blocks in the
system and report them via a callback function. Some page blocks may
leave the free list after zone->lock is released, so it is the caller's
responsibility to either detect or prevent the use of such pages.
One use example of this patch is to accelerate live migration by skipping
the transfer of free pages reported from the guest. A popular method used
by the hypervisor to track which part of memory is written during live
migration is to write-protect all the guest memory. So, those pages that
are reported as free pages but are written after the report function
returns will be captured by the hypervisor, and they will be added to the
next round of memory transfer.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Michal Hocko <mhocko@kernel.org>
---
include/linux/mm.h | 6 ++++
mm/page_alloc.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 97 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ea818ff..b3077dd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1938,6 +1938,12 @@ extern void free_area_init_node(int nid, unsigned long * zones_size,
unsigned long zone_start_pfn, unsigned long *zholes_size);
extern void free_initmem(void);
+extern void walk_free_mem_block(void *opaque,
+ int min_order,
+ bool (*report_pfn_range)(void *opaque,
+ unsigned long pfn,
+ unsigned long num));
+
/*
* Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
* into the buddy system. The freed pages will be poisoned with pattern
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7e5e775..f074503 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4899,6 +4899,97 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
show_swap_cache_info();
}
+/*
+ * Walk through a free page list and report the found pfn range via the
+ * callback.
+ *
+ * Return false if the callback requests to stop reporting. Otherwise,
+ * return true.
+ */
+static bool walk_free_page_list(void *opaque,
+ struct zone *zone,
+ int order,
+ enum migratetype mt,
+ bool (*report_pfn_range)(void *,
+ unsigned long,
+ unsigned long))
+{
+ struct page *page;
+ struct list_head *list;
+ unsigned long pfn, flags;
+ bool ret;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ list = &zone->free_area[order].free_list[mt];
+ list_for_each_entry(page, list, lru) {
+ pfn = page_to_pfn(page);
+ ret = report_pfn_range(opaque, pfn, 1 << order);
+ if (!ret)
+ break;
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ return ret;
+}
+
+/**
+ * walk_free_mem_block - Walk through the free page blocks in the system
+ * @opaque: the context passed from the caller
+ * @min_order: the minimum order of free lists to check
+ * @report_pfn_range: the callback to report the pfn range of the free pages
+ *
+ * If the callback returns false, stop iterating the list of free page blocks.
+ * Otherwise, continue to report.
+ *
+ * Please note that there are no locking guarantees for the callback and
+ * that the reported pfn range might be freed or disappear after the
+ * callback returns so the caller has to be very careful how it is used.
+ *
+ * The callback itself must not sleep or perform any operations which would
+ * require any memory allocations directly (not even GFP_NOWAIT/GFP_ATOMIC)
+ * or via any lock dependency. It is generally advisable to implement
+ * the callback as simple as possible and defer any heavy lifting to a
+ * different context.
+ *
+ * There is no guarantee that each free range will be reported only once
+ * during one walk_free_mem_block invocation.
+ *
+ * pfn_to_page on the given range is strongly discouraged and if there is
+ * an absolute need for that make sure to contact MM people to discuss
+ * potential problems.
+ *
+ * The function itself might sleep so it cannot be called from atomic
+ * contexts.
+ *
+ * In general low orders tend to be very volatile and so it makes more
+ * sense to query larger ones first for various optimizations which like
+ * ballooning etc... This will reduce the overhead as well.
+ */
+void walk_free_mem_block(void *opaque,
+ int min_order,
+ bool (*report_pfn_range)(void *opaque,
+ unsigned long pfn,
+ unsigned long num))
+{
+ struct zone *zone;
+ int order;
+ enum migratetype mt;
+ bool ret;
+
+ for_each_populated_zone(zone) {
+ for (order = MAX_ORDER - 1; order >= min_order; order--) {
+ for (mt = 0; mt < MIGRATE_TYPES; mt++) {
+ ret = walk_free_page_list(opaque, zone,
+ order, mt,
+ report_pfn_range);
+ if (!ret)
+ return;
+ }
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(walk_free_mem_block);
+
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
--
2.7.4
^ permalink raw reply related
* [PATCH v20 4/7] virtio-balloon: VIRTIO_BALLOON_F_SG
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
Add a new feature, VIRTIO_BALLOON_F_SG, which enables the transfer of
balloon (i.e. inflated/deflated) pages using scatter-gather lists to the
host.
The implementation of the previous virtio-balloon is not very efficient,
because the balloon pages are transferred to the host by one array each
time. Here is the breakdown of the time in percentage spent on each step
of the balloon inflating process (inflating 7GB of an 8GB idle guest).
1) allocating pages (6.5%)
2) sending PFNs to host (68.3%)
3) address translation (6.1%)
4) madvise (19%)
It takes about 4126ms for the inflating process to complete. The above
profiling shows that the bottlenecks are stage 2) and stage 4).
This patch optimizes step 2) by transferring pages to host in sgs. An sg
describes a chunk of guest physically continuous pages. With this
mechanism, step 4) can also be optimized by doing address translation and
madvise() in chunks rather than page by page.
With this new feature, the above ballooning process takes ~460ms resulting
in an improvement of ~89%.
TODO:
- optimize stage 1) by allocating/freeing a chunk of pages instead of a
single page each time.
- sort the internal balloon page queue.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
drivers/virtio/virtio_balloon.c | 234 +++++++++++++++++++++++++++++++++---
include/uapi/linux/virtio_balloon.h | 1 +
2 files changed, 217 insertions(+), 18 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index a1fb52c..fff0a3f 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -32,6 +32,8 @@
#include <linux/mm.h>
#include <linux/mount.h>
#include <linux/magic.h>
+#include <linux/xbitmap.h>
+#include <asm/page.h>
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -79,6 +81,9 @@ struct virtio_balloon {
/* Synchronize access/update to this struct virtio_balloon elements */
struct mutex balloon_lock;
+ /* The xbitmap used to record balloon pages */
+ struct xb page_xb;
+
/* The array of pfns we tell the Host about. */
unsigned int num_pfns;
__virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
@@ -141,15 +146,129 @@ static void set_page_pfns(struct virtio_balloon *vb,
page_to_balloon_pfn(page) + i);
}
+static void kick_and_wait(struct virtqueue *vq, wait_queue_head_t wq_head)
+{
+ unsigned int len;
+
+ virtqueue_kick(vq);
+ wait_event(wq_head, virtqueue_get_buf(vq, &len));
+}
+
+static void add_one_sg(struct virtqueue *vq, unsigned long pfn, uint32_t len)
+{
+ struct scatterlist sg;
+ unsigned int unused;
+ int err;
+
+ sg_init_table(&sg, 1);
+ sg_set_page(&sg, pfn_to_page(pfn), len, 0);
+
+ /* Detach all the used buffers from the vq */
+ while (virtqueue_get_buf(vq, &unused))
+ ;
+
+ err = virtqueue_add_inbuf(vq, &sg, 1, vq, GFP_KERNEL);
+ /*
+ * This is expected to never fail: there is always at least 1 entry
+ * available on the vq, because when the vq is full the worker thread
+ * that adds the sg will be put into sleep until at least 1 entry is
+ * available to use.
+ */
+ BUG_ON(err);
+}
+
+static void batch_balloon_page_sg(struct virtio_balloon *vb,
+ struct virtqueue *vq,
+ unsigned long pfn,
+ uint32_t len)
+{
+ add_one_sg(vq, pfn, len);
+
+ /* Batch till the vq is full */
+ if (!vq->num_free)
+ kick_and_wait(vq, vb->acked);
+}
+
+/*
+ * Send balloon pages in sgs to host. The balloon pages are recorded in the
+ * page xbitmap. Each bit in the bitmap corresponds to a page of PAGE_SIZE.
+ * The page xbitmap is searched for continuous "1" bits, which correspond
+ * to continuous pages, to chunk into sgs.
+ *
+ * @page_xb_start and @page_xb_end form the range of bits in the xbitmap that
+ * need to be searched.
+ */
+static void tell_host_sgs(struct virtio_balloon *vb,
+ struct virtqueue *vq,
+ unsigned long page_xb_start,
+ unsigned long page_xb_end)
+{
+ unsigned long pfn_start, pfn_end;
+ uint32_t max_len = round_down(UINT_MAX, PAGE_SIZE);
+ uint64_t len;
+
+ pfn_start = page_xb_start;
+ while (pfn_start < page_xb_end) {
+ pfn_start = xb_find_set(&vb->page_xb, page_xb_end + 1,
+ pfn_start);
+ if (pfn_start == page_xb_end + 1)
+ break;
+ pfn_end = xb_find_zero(&vb->page_xb, page_xb_end + 1,
+ pfn_start);
+ len = (pfn_end - pfn_start) << PAGE_SHIFT;
+ while (len > max_len) {
+ batch_balloon_page_sg(vb, vq, pfn_start, max_len);
+ pfn_start += max_len >> PAGE_SHIFT;
+ len -= max_len;
+ }
+ batch_balloon_page_sg(vb, vq, pfn_start, (uint32_t)len);
+ pfn_start = pfn_end + 1;
+ }
+
+ /*
+ * The last few sgs may not reach the batch size, but need a kick to
+ * notify the device to handle them.
+ */
+ if (vq->num_free != virtqueue_get_vring_size(vq))
+ kick_and_wait(vq, vb->acked);
+
+ xb_clear_bit_range(&vb->page_xb, page_xb_start, page_xb_end);
+}
+
+static inline int xb_set_page(struct virtio_balloon *vb,
+ struct page *page,
+ unsigned long *pfn_min,
+ unsigned long *pfn_max)
+{
+ unsigned long pfn = page_to_pfn(page);
+ int ret;
+
+ *pfn_min = min(pfn, *pfn_min);
+ *pfn_max = max(pfn, *pfn_max);
+
+ do {
+ if (xb_preload(GFP_NOWAIT | __GFP_NOWARN) < 0)
+ return -ENOMEM;
+
+ ret = xb_set_bit(&vb->page_xb, pfn);
+ xb_preload_end();
+ } while (unlikely(ret == -EAGAIN));
+
+ return ret;
+}
+
static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
{
unsigned num_allocated_pages;
unsigned num_pfns;
struct page *page;
LIST_HEAD(pages);
+ bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
+ unsigned long pfn_max = 0, pfn_min = ULONG_MAX;
/* We can only do one array worth at a time. */
- num = min(num, ARRAY_SIZE(vb->pfns));
+ if (!use_sg)
+ num = min(num, ARRAY_SIZE(vb->pfns));
for (num_pfns = 0; num_pfns < num;
num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
@@ -173,8 +292,15 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
while ((page = balloon_page_pop(&pages))) {
balloon_page_enqueue(&vb->vb_dev_info, page);
+ if (use_sg) {
+ if (xb_set_page(vb, page, &pfn_min, &pfn_max) < 0) {
+ __free_page(page);
+ continue;
+ }
+ } else {
+ set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ }
- set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
if (!virtio_has_feature(vb->vdev,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
@@ -184,8 +310,12 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
num_allocated_pages = vb->num_pfns;
/* Did we get any? */
- if (vb->num_pfns != 0)
- tell_host(vb, vb->inflate_vq);
+ if (vb->num_pfns) {
+ if (use_sg)
+ tell_host_sgs(vb, vb->inflate_vq, pfn_min, pfn_max);
+ else
+ tell_host(vb, vb->inflate_vq);
+ }
mutex_unlock(&vb->balloon_lock);
return num_allocated_pages;
@@ -211,9 +341,12 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
struct page *page;
struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
LIST_HEAD(pages);
+ bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
+ unsigned long pfn_max = 0, pfn_min = ULONG_MAX;
- /* We can only do one array worth at a time. */
- num = min(num, ARRAY_SIZE(vb->pfns));
+ /* Traditionally, we can only do one array worth at a time. */
+ if (!use_sg)
+ num = min(num, ARRAY_SIZE(vb->pfns));
mutex_lock(&vb->balloon_lock);
/* We can't release more pages than taken */
@@ -223,7 +356,14 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
page = balloon_page_dequeue(vb_dev_info);
if (!page)
break;
- set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ if (use_sg) {
+ if (xb_set_page(vb, page, &pfn_min, &pfn_max) < 0) {
+ balloon_page_enqueue(&vb->vb_dev_info, page);
+ break;
+ }
+ } else {
+ set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ }
list_add(&page->lru, &pages);
vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
}
@@ -234,13 +374,55 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
* virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
* is true, we *have* to do it in this order
*/
- if (vb->num_pfns != 0)
- tell_host(vb, vb->deflate_vq);
+ if (vb->num_pfns) {
+ if (use_sg)
+ tell_host_sgs(vb, vb->deflate_vq, pfn_min, pfn_max);
+ else
+ tell_host(vb, vb->deflate_vq);
+ }
release_pages_balloon(vb, &pages);
mutex_unlock(&vb->balloon_lock);
return num_freed_pages;
}
+/*
+ * The regular leak_balloon() with VIRTIO_BALLOON_F_SG needs memory allocation
+ * for xbitmap, which is not suitable for the oom case. This function does not
+ * use xbitmap to chunk pages, so it can be used by oom notifier to deflate
+ * pages when VIRTIO_BALLOON_F_SG is negotiated.
+ */
+static unsigned int leak_balloon_sg_oom(struct virtio_balloon *vb)
+{
+ unsigned int n;
+ struct page *page;
+ struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
+ struct virtqueue *vq = vb->deflate_vq;
+ LIST_HEAD(pages);
+
+ mutex_lock(&vb->balloon_lock);
+ for (n = 0; n < oom_pages; n++) {
+ page = balloon_page_dequeue(vb_dev_info);
+ if (!page)
+ break;
+
+ list_add(&page->lru, &pages);
+ vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
+ batch_balloon_page_sg(vb, vb->deflate_vq, page_to_pfn(page),
+ PAGE_SIZE);
+ release_pages_balloon(vb, &pages);
+ }
+
+ /*
+ * The last few sgs may not reach the batch size, but need a kick to
+ * notify the device to handle them.
+ */
+ if (vq->num_free != virtqueue_get_vring_size(vq))
+ kick_and_wait(vq, vb->acked);
+ mutex_unlock(&vb->balloon_lock);
+
+ return n;
+}
+
static inline void update_stat(struct virtio_balloon *vb, int idx,
u16 tag, u64 val)
{
@@ -380,7 +562,10 @@ static int virtballoon_oom_notify(struct notifier_block *self,
return NOTIFY_OK;
freed = parm;
- num_freed_pages = leak_balloon(vb, oom_pages);
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG))
+ num_freed_pages = leak_balloon_sg_oom(vb);
+ else
+ num_freed_pages = leak_balloon(vb, oom_pages);
update_balloon_size(vb);
*freed += num_freed_pages;
@@ -477,6 +662,7 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
{
struct virtio_balloon *vb = container_of(vb_dev_info,
struct virtio_balloon, vb_dev_info);
+ bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
unsigned long flags;
/*
@@ -498,16 +684,24 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
vb_dev_info->isolated_pages--;
__count_vm_event(BALLOON_MIGRATE);
spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
- vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
- set_page_pfns(vb, vb->pfns, newpage);
- tell_host(vb, vb->inflate_vq);
-
+ if (use_sg) {
+ add_one_sg(vb->inflate_vq, page_to_pfn(newpage), PAGE_SIZE);
+ kick_and_wait(vb->inflate_vq, vb->acked);
+ } else {
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb, vb->pfns, newpage);
+ tell_host(vb, vb->inflate_vq);
+ }
/* balloon's page migration 2nd step -- deflate "page" */
balloon_page_delete(page);
- vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
- set_page_pfns(vb, vb->pfns, page);
- tell_host(vb, vb->deflate_vq);
-
+ if (use_sg) {
+ add_one_sg(vb->deflate_vq, page_to_pfn(page), PAGE_SIZE);
+ kick_and_wait(vb->deflate_vq, vb->acked);
+ } else {
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb, vb->pfns, page);
+ tell_host(vb, vb->deflate_vq);
+ }
mutex_unlock(&vb->balloon_lock);
put_page(page); /* balloon reference */
@@ -566,6 +760,9 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (err)
goto out_free_vb;
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_SG))
+ xb_init(&vb->page_xb);
+
vb->nb.notifier_call = virtballoon_oom_notify;
vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
err = register_oom_notifier(&vb->nb);
@@ -682,6 +879,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_MUST_TELL_HOST,
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
+ VIRTIO_BALLOON_F_SG,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 343d7dd..37780a7 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -34,6 +34,7 @@
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
+#define VIRTIO_BALLOON_F_SG 3 /* Use sg instead of PFN lists */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
--
2.7.4
^ permalink raw reply related
* [PATCH v20 3/7] xbitmap: add more operations
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
This patch adds support to find next 1 or 0 bit in a xbmitmap range and
clear a range of bits.
More possible optimizations to add in the future:
1) xb_set_bit_range: set a range of bits.
2) when searching a bit, if the bit is not found in the slot, move on to
the next slot directly.
3) add tags to help searching.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Suggested-by: Matthew Wilcox <mawilcox@microsoft.com>
---
include/linux/xbitmap.h | 6 ++
lib/xbitmap.c | 198 +++++++++++++++++++++++++++++++++++++++++++
tools/include/linux/bitmap.h | 34 ++++++++
tools/include/linux/kernel.h | 2 +
4 files changed, 240 insertions(+)
diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
index 108f929..ede1029 100644
--- a/include/linux/xbitmap.h
+++ b/include/linux/xbitmap.h
@@ -35,6 +35,12 @@ static inline void xb_init(struct xb *xb)
int xb_set_bit(struct xb *xb, unsigned long bit);
bool xb_test_bit(const struct xb *xb, unsigned long bit);
void xb_clear_bit(struct xb *xb, unsigned long bit);
+void xb_clear_bit_range(struct xb *xb, unsigned long start,
+ unsigned long nbits);
+unsigned long xb_find_set(struct xb *xb, unsigned long size,
+ unsigned long offset);
+unsigned long xb_find_zero(struct xb *xb, unsigned long size,
+ unsigned long offset);
static inline bool xb_empty(const struct xb *xb)
{
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
index 2dcfad5..bb0a5b2 100644
--- a/lib/xbitmap.c
+++ b/lib/xbitmap.c
@@ -3,6 +3,16 @@
#include <linux/bitmap.h>
#include <linux/slab.h>
+/*
+ * Developer notes:
+ * - locks are required to gurantee there is no concurrent
+ * calls of xb_set_bit, xb_clear_bit, xb_clear_bit_range, xb_test_bit,
+ * xb_find_set, or xb_find_clear to operate on the same ida bitmap.
+ * - The current implementation of xb_clear_bit_range, xb_find_set and
+ * xb_find_clear may cause long latency when the bit range to operate
+ * on is super large (e.g. [0, ULONG_MAX)).
+ */
+
/**
* xb_set_bit - set a bit in the xbitmap
* @xb: the xbitmap tree used to record the bit
@@ -72,6 +82,49 @@ void xb_clear_bit(struct xb *xb, unsigned long bit)
EXPORT_SYMBOL(xb_clear_bit);
/**
+ * xb_clear_bit_range - clear a range of bits in the xbitmap
+ * @start: the start of the bit range, inclusive
+ * @nbits: number of bits to clear
+ *
+ * This function is used to clear a range of bits in the xbitmap. If all the
+ * bits in the bitmap are 0, the bitmap will be freed.
+ */
+void xb_clear_bit_range(struct xb *xb, unsigned long start,
+ unsigned long nbits)
+{
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void __rcu **slot;
+ struct ida_bitmap *bitmap;
+ unsigned long index = start / IDA_BITMAP_BITS;
+ unsigned long bit = start % IDA_BITMAP_BITS;
+
+ if (nbits > ULONG_MAX - start)
+ nbits = ULONG_MAX - start;
+
+ while (nbits) {
+ unsigned int __nbits = min(nbits,
+ (unsigned long)IDA_BITMAP_BITS - bit);
+
+ bitmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (bitmap) {
+ if (__nbits != IDA_BITMAP_BITS)
+ bitmap_clear(bitmap->bitmap, bit, __nbits);
+
+ if (__nbits == IDA_BITMAP_BITS ||
+ bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
+ kfree(bitmap);
+ __radix_tree_delete(root, node, slot);
+ }
+ }
+ bit = 0;
+ index++;
+ nbits -= __nbits;
+ }
+}
+EXPORT_SYMBOL(xb_clear_bit_range);
+
+/**
* xb_test_bit - test a bit in the xbitmap
* @xb: the xbitmap tree used to record the bit
* @bit: index of the bit to test
@@ -94,6 +147,99 @@ bool xb_test_bit(const struct xb *xb, unsigned long bit)
}
EXPORT_SYMBOL(xb_test_bit);
+/**
+ * xb_find_set - find the next set bit in a range of bits
+ * @xb: the xbitmap to search from
+ * @offset: the offset in the range to start searching
+ * @size: the size of the range
+ *
+ * Returns: the found bit or, @size if no set bit is found.
+ */
+unsigned long xb_find_set(struct xb *xb, unsigned long size,
+ unsigned long offset)
+{
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void __rcu **slot;
+ struct ida_bitmap *bitmap;
+ unsigned long index = offset / IDA_BITMAP_BITS;
+ unsigned long index_end = size / IDA_BITMAP_BITS;
+ unsigned long bit = offset % IDA_BITMAP_BITS;
+
+ if (unlikely(offset >= size))
+ return size;
+
+ while (index <= index_end) {
+ unsigned long ret;
+ unsigned int nbits = size - index * IDA_BITMAP_BITS;
+
+ bitmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (!node) {
+ index = (index | RADIX_TREE_MAP_MASK) + 1;
+ continue;
+ }
+
+ if (bitmap) {
+ if (nbits > IDA_BITMAP_BITS)
+ nbits = IDA_BITMAP_BITS;
+
+ ret = find_next_bit(bitmap->bitmap, nbits, bit);
+ if (ret != nbits)
+ return ret + index * IDA_BITMAP_BITS;
+ }
+ bit = 0;
+ index++;
+ }
+
+ return size;
+}
+EXPORT_SYMBOL(xb_find_set);
+
+/**
+ * xb_find_zero - find the next zero bit in a range of bits
+ * @xb: the xbitmap to search from
+ * @offset: the offset in the range to start searching
+ * @size: the size of the range
+ *
+ * Returns: the found bit or, @size if no zero bit is found.
+ */
+unsigned long xb_find_zero(struct xb *xb, unsigned long size,
+ unsigned long offset)
+{
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void __rcu **slot;
+ struct ida_bitmap *bitmap;
+ unsigned long index = offset / IDA_BITMAP_BITS;
+ unsigned long index_end = size / IDA_BITMAP_BITS;
+ unsigned long bit = offset % IDA_BITMAP_BITS;
+
+ if (unlikely(offset >= size))
+ return size;
+
+ while (index <= index_end) {
+ unsigned long ret;
+ unsigned int nbits = size - index * IDA_BITMAP_BITS;
+
+ bitmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (bitmap) {
+ if (nbits > IDA_BITMAP_BITS)
+ nbits = IDA_BITMAP_BITS;
+
+ ret = find_next_zero_bit(bitmap->bitmap, nbits, bit);
+ if (ret != nbits)
+ return ret + index * IDA_BITMAP_BITS;
+ } else {
+ return bit + index * IDA_BITMAP_BITS;
+ }
+ bit = 0;
+ index++;
+ }
+
+ return size;
+}
+EXPORT_SYMBOL(xb_find_zero);
+
#ifndef __KERNEL__
static DEFINE_XB(xb1);
@@ -111,6 +257,56 @@ void xbitmap_check_bit(unsigned long bit)
xb_preload_end();
}
+static void xbitmap_check_bit_range(void)
+{
+ /*
+ * Regular tests
+ * set bit 2000, 2001, 2040
+ * Next 1 in [0, 2048) --> 2000
+ * Next 1 in [2000, 2002) --> 2000
+ * Next 1 in [2002, 2041) --> 2040
+ * Next 1 in [2002, 2040) --> none
+ * Next 0 in [2000, 2048) --> 2002
+ * Next 0 in [2048, 2060) --> 2048
+ */
+ xb_preload(GFP_KERNEL);
+ assert(!xb_set_bit(&xb1, 2000));
+ assert(!xb_set_bit(&xb1, 2001));
+ assert(!xb_set_bit(&xb1, 2040));
+ assert(xb_find_set(&xb1, 2048, 0) == 2000);
+ assert(xb_find_set(&xb1, 2002, 2000) == 2000);
+ assert(xb_find_set(&xb1, 2041, 2002) == 2040);
+ assert(xb_find_set(&xb1, 2040, 2002) == 2040);
+ assert(xb_find_zero(&xb1, 2048, 2000) == 2002);
+ assert(xb_find_zero(&xb1, 2060, 2048) == 2048);
+ xb_clear_bit_range(&xb1, 0, 2048);
+ assert(xb_find_set(&xb1, 2048, 0) == 2048);
+ xb_preload_end();
+
+ /*
+ * Overflow tests:
+ * Set bit 1 and ULONG_MAX - 4
+ * Next 1 in [ULONG_MAX - 4, ULONG_MAX) --> ULONG_MAX - 4
+ * Next 1 [ULONG_MAX - 3, ULONG_MAX + 4) --> none
+ * Next 0 [ULONG_MAX - 4, ULONG_MAX + 4) --> none
+ */
+ xb_preload(GFP_KERNEL);
+ assert(!xb_set_bit(&xb1, 1));
+ xb_preload_end();
+ xb_preload(GFP_KERNEL);
+ assert(!xb_set_bit(&xb1, ULONG_MAX - 4));
+ assert(xb_find_set(&xb1, ULONG_MAX, ULONG_MAX - 4) == ULONG_MAX - 4);
+ assert(xb_find_set(&xb1, ULONG_MAX + 4, ULONG_MAX - 3) ==
+ ULONG_MAX + 4);
+ assert(xb_find_zero(&xb1, ULONG_MAX + 4, ULONG_MAX - 4) ==
+ ULONG_MAX + 4);
+ xb_clear_bit_range(&xb1, ULONG_MAX - 4, 4);
+ assert(xb_find_set(&xb1, ULONG_MAX, ULONG_MAX - 10) == ULONG_MAX);
+ xb_clear_bit_range(&xb1, 0, 2);
+ assert(xb_find_set(&xb1, 2, 0) == 2);
+ xb_preload_end();
+}
+
void xbitmap_checks(void)
{
xb_init(&xb1);
@@ -122,6 +318,8 @@ void xbitmap_checks(void)
xbitmap_check_bit(1025);
xbitmap_check_bit((1UL << 63) | (1UL << 24));
xbitmap_check_bit((1UL << 63) | (1UL << 24) | 70);
+
+ xbitmap_check_bit_range();
}
int __weak main(void)
diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index ca16027..8d0bc1b 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -37,6 +37,40 @@ static inline void bitmap_zero(unsigned long *dst, int nbits)
}
}
+static inline void __bitmap_clear(unsigned long *map, unsigned int start,
+ int len)
+{
+ unsigned long *p = map + BIT_WORD(start);
+ const unsigned int size = start + len;
+ int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+ unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+ while (len - bits_to_clear >= 0) {
+ *p &= ~mask_to_clear;
+ len -= bits_to_clear;
+ bits_to_clear = BITS_PER_LONG;
+ mask_to_clear = ~0UL;
+ p++;
+ }
+ if (len) {
+ mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+ *p &= ~mask_to_clear;
+ }
+}
+
+static inline __always_inline void bitmap_clear(unsigned long *map,
+ unsigned int start,
+ unsigned int nbits)
+{
+ if (__builtin_constant_p(nbits) && nbits == 1)
+ __clear_bit(start, map);
+ else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
+ __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
+ memset((char *)map + start / 8, 0, nbits / 8);
+ else
+ __bitmap_clear(map, start, nbits);
+}
+
static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
{
unsigned int nlongs = BITS_TO_LONGS(nbits);
diff --git a/tools/include/linux/kernel.h b/tools/include/linux/kernel.h
index 0ad8844..3c992ae 100644
--- a/tools/include/linux/kernel.h
+++ b/tools/include/linux/kernel.h
@@ -13,6 +13,8 @@
#define UINT_MAX (~0U)
#endif
+#define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
+
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define PERF_ALIGN(x, a) __PERF_ALIGN_MASK(x, (typeof(x))(a)-1)
--
2.7.4
^ permalink raw reply related
* [PATCH v20 2/7] xbitmap: potential improvement
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
This patch made some changes to the original xbitmap implementation from
the linux-dax tree:
- xb_set_bit: delete the new inserted radix_tree_node when failing to
get the per cpu ida bitmap, this avoids the kind of memory leak of the
unused radix tree node left in the tree.
- xb_preload: with the original implementation, the CPU that successfully
do __radix_tree_preload() may get into sleep by kmalloc(), which has a
risk of getting the caller of xb_preload() scheduled to another CPU
after waken up, and the new CPU may not have radix_tree_node
pre-allocated there, this will be a problem when inserting a node to
the tree later. This patch moves __radix_tree_preload() after kmalloc()
and returns a boolean to indicate the success or failure. Also, add the
__must_check annotation to xb_preload for prudence purpose.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
include/linux/xbitmap.h | 2 +-
lib/radix-tree.c | 21 ++++++++++++++++++---
lib/xbitmap.c | 4 +++-
3 files changed, 22 insertions(+), 5 deletions(-)
diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
index 4ac2b8d..108f929 100644
--- a/include/linux/xbitmap.h
+++ b/include/linux/xbitmap.h
@@ -41,7 +41,7 @@ static inline bool xb_empty(const struct xb *xb)
return radix_tree_empty(&xb->xbrt);
}
-void xb_preload(gfp_t);
+int xb_preload(gfp_t);
static inline void xb_preload_end(void)
{
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 2650e9e..f30347a 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -2142,17 +2142,32 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
}
EXPORT_SYMBOL(ida_pre_get);
-void xb_preload(gfp_t gfp)
+/**
+ * xb_preload - preload for xb_set_bit()
+ * @gfp_mask: allocation mask to use for preloading
+ *
+ * Preallocate memory to use for the next call to xb_set_bit(). On success,
+ * return zero, with preemption disabled. On error, return -ENOMEM with
+ * preemption not disabled.
+ */
+__must_check int xb_preload(gfp_t gfp)
{
- __radix_tree_preload(gfp, XB_PRELOAD_SIZE);
if (!this_cpu_read(ida_bitmap)) {
struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp);
if (!bitmap)
- return;
+ return -ENOMEM;
+ /*
+ * The per-CPU variable is updated with preemption enabled.
+ * If the calling task is unlucky to be scheduled to another
+ * CPU which has no ida_bitmap allocation, it will be detected
+ * when setting a bit (i.e. xb_set_bit()).
+ */
bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);
kfree(bitmap);
}
+
+ return __radix_tree_preload(gfp, XB_PRELOAD_SIZE);
}
EXPORT_SYMBOL(xb_preload);
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
index 236afa9..2dcfad5 100644
--- a/lib/xbitmap.c
+++ b/lib/xbitmap.c
@@ -29,8 +29,10 @@ int xb_set_bit(struct xb *xb, unsigned long bit)
bitmap = rcu_dereference_raw(*slot);
if (!bitmap) {
bitmap = this_cpu_xchg(ida_bitmap, NULL);
- if (!bitmap)
+ if (!bitmap) {
+ __radix_tree_delete(root, node, slot);
return -EAGAIN;
+ }
memset(bitmap, 0, sizeof(*bitmap));
__radix_tree_replace(root, node, slot, bitmap, NULL);
}
--
2.7.4
^ permalink raw reply related
* [PATCH v20 1/7] xbitmap: Introduce xbitmap
From: Wei Wang @ 2017-12-19 12:17 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, quan.xu0, penguin-kernel,
liliang.opensource, willy, amit.shah, cornelia.huck, pbonzini,
nilal, mgorman
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
From: Matthew Wilcox <mawilcox@microsoft.com>
The eXtensible Bitmap is a sparse bitmap representation which is
efficient for set bits which tend to cluster. It supports up to
'unsigned long' worth of bits, and this commit adds the bare bones --
xb_set_bit(), xb_clear_bit() and xb_test_bit().
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
include/linux/radix-tree.h | 2 +
include/linux/xbitmap.h | 49 ++++++++++++
lib/Makefile | 2 +-
lib/radix-tree.c | 25 +++++-
lib/xbitmap.c | 130 +++++++++++++++++++++++++++++++
tools/testing/radix-tree/Makefile | 12 ++-
tools/testing/radix-tree/linux/xbitmap.h | 1 +
tools/testing/radix-tree/main.c | 4 +
tools/testing/radix-tree/test.h | 1 +
9 files changed, 221 insertions(+), 5 deletions(-)
create mode 100644 include/linux/xbitmap.h
create mode 100644 lib/xbitmap.c
create mode 100644 tools/testing/radix-tree/linux/xbitmap.h
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 23a9c89..5c16179a 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -315,6 +315,8 @@ void radix_tree_iter_delete(struct radix_tree_root *,
struct radix_tree_iter *iter, void __rcu **slot);
void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
+bool __radix_tree_delete(struct radix_tree_root *r, struct radix_tree_node *n,
+ void __rcu **slot);
void radix_tree_clear_tags(struct radix_tree_root *, struct radix_tree_node *,
void __rcu **slot);
unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
new file mode 100644
index 0000000..4ac2b8d
--- /dev/null
+++ b/include/linux/xbitmap.h
@@ -0,0 +1,49 @@
+/*
+ * eXtensible Bitmaps
+ * Copyright (c) 2017 Microsoft Corporation <mawilcox@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * eXtensible Bitmaps provide an unlimited-size sparse bitmap facility.
+ * All bits are initially zero.
+ */
+
+#include <linux/idr.h>
+
+struct xb {
+ struct radix_tree_root xbrt;
+};
+
+#define XB_INIT { \
+ .xbrt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT), \
+}
+#define DEFINE_XB(name) struct xb name = XB_INIT
+
+static inline void xb_init(struct xb *xb)
+{
+ INIT_RADIX_TREE(&xb->xbrt, IDR_RT_MARKER | GFP_NOWAIT);
+}
+
+int xb_set_bit(struct xb *xb, unsigned long bit);
+bool xb_test_bit(const struct xb *xb, unsigned long bit);
+void xb_clear_bit(struct xb *xb, unsigned long bit);
+
+static inline bool xb_empty(const struct xb *xb)
+{
+ return radix_tree_empty(&xb->xbrt);
+}
+
+void xb_preload(gfp_t);
+
+static inline void xb_preload_end(void)
+{
+ preempt_enable();
+}
diff --git a/lib/Makefile b/lib/Makefile
index d11c48e..08a8183 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -19,7 +19,7 @@ KCOV_INSTRUMENT_dynamic_debug.o := n
lib-y := ctype.o string.o vsprintf.o cmdline.o \
rbtree.o radix-tree.o dump_stack.o timerqueue.o\
- idr.o int_sqrt.o extable.o \
+ idr.o xbitmap.o int_sqrt.o extable.o \
sha1.o chacha20.o irq_regs.o argv_split.o \
flex_proportions.o ratelimit.o show_mem.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index c8d5556..2650e9e 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -37,7 +37,7 @@
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/string.h>
-
+#include <linux/xbitmap.h>
/* Number of nodes in fully populated tree of given height */
static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
@@ -77,6 +77,11 @@ static struct kmem_cache *radix_tree_node_cachep;
RADIX_TREE_MAP_SHIFT))
#define IDA_PRELOAD_SIZE (IDA_MAX_PATH * 2 - 1)
+#define XB_INDEX_BITS (BITS_PER_LONG - ilog2(IDA_BITMAP_BITS))
+#define XB_MAX_PATH (DIV_ROUND_UP(XB_INDEX_BITS, \
+ RADIX_TREE_MAP_SHIFT))
+#define XB_PRELOAD_SIZE (XB_MAX_PATH * 2 - 1)
+
/*
* Per-cpu pool of preloaded nodes
*/
@@ -839,6 +844,8 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
offset, 0, 0);
if (!child)
return -ENOMEM;
+ if (is_idr(root))
+ all_tag_set(child, IDR_FREE);
rcu_assign_pointer(*slot, node_to_entry(child));
if (node)
node->count++;
@@ -1982,7 +1989,7 @@ void __radix_tree_delete_node(struct radix_tree_root *root,
delete_node(root, node, update_node);
}
-static bool __radix_tree_delete(struct radix_tree_root *root,
+bool __radix_tree_delete(struct radix_tree_root *root,
struct radix_tree_node *node, void __rcu **slot)
{
void *old = rcu_dereference_raw(*slot);
@@ -2135,6 +2142,20 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
}
EXPORT_SYMBOL(ida_pre_get);
+void xb_preload(gfp_t gfp)
+{
+ __radix_tree_preload(gfp, XB_PRELOAD_SIZE);
+ if (!this_cpu_read(ida_bitmap)) {
+ struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp);
+
+ if (!bitmap)
+ return;
+ bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);
+ kfree(bitmap);
+ }
+}
+EXPORT_SYMBOL(xb_preload);
+
void __rcu **idr_get_free_cmn(struct radix_tree_root *root,
struct radix_tree_iter *iter, gfp_t gfp,
unsigned long max)
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
new file mode 100644
index 0000000..236afa9
--- /dev/null
+++ b/lib/xbitmap.c
@@ -0,0 +1,130 @@
+#include <linux/export.h>
+#include <linux/xbitmap.h>
+#include <linux/bitmap.h>
+#include <linux/slab.h>
+
+/**
+ * xb_set_bit - set a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to set
+ *
+ * This function is used to set a bit in the xbitmap. If the bitmap that @bit
+ * resides in is not there, the per-cpu ida_bitmap will be taken.
+ *
+ * Returns: 0 on success. -EAGAIN or -ENOMEM indicates that @bit is not set.
+ */
+int xb_set_bit(struct xb *xb, unsigned long bit)
+{
+ int err;
+ unsigned long index = bit / IDA_BITMAP_BITS;
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void __rcu **slot;
+ struct ida_bitmap *bitmap;
+
+ bit %= IDA_BITMAP_BITS;
+ err = __radix_tree_create(root, index, 0, &node, &slot);
+ if (err)
+ return err;
+ bitmap = rcu_dereference_raw(*slot);
+ if (!bitmap) {
+ bitmap = this_cpu_xchg(ida_bitmap, NULL);
+ if (!bitmap)
+ return -EAGAIN;
+ memset(bitmap, 0, sizeof(*bitmap));
+ __radix_tree_replace(root, node, slot, bitmap, NULL);
+ }
+
+ __set_bit(bit, bitmap->bitmap);
+ return 0;
+}
+EXPORT_SYMBOL(xb_set_bit);
+
+/**
+ * xb_clear_bit - clear a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to clear
+ *
+ * This function is used to clear a bit in the xbitmap. If all the bits of the
+ * bitmap are 0, the bitmap will be freed.
+ */
+void xb_clear_bit(struct xb *xb, unsigned long bit)
+{
+ unsigned long index = bit / IDA_BITMAP_BITS;
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void __rcu **slot;
+ struct ida_bitmap *bitmap;
+
+ bit %= IDA_BITMAP_BITS;
+ bitmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (!bitmap)
+ return;
+
+ __clear_bit(bit, bitmap->bitmap);
+ if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
+ kfree(bitmap);
+ __radix_tree_delete(root, node, slot);
+ }
+}
+EXPORT_SYMBOL(xb_clear_bit);
+
+/**
+ * xb_test_bit - test a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to test
+ *
+ * This function is used to test a bit in the xbitmap.
+ *
+ * Returns: true if the bit is set, or false otherwise.
+ */
+bool xb_test_bit(const struct xb *xb, unsigned long bit)
+{
+ unsigned long index = bit / IDA_BITMAP_BITS;
+ const struct radix_tree_root *root = &xb->xbrt;
+ struct ida_bitmap *bitmap = radix_tree_lookup(root, index);
+
+ bit %= IDA_BITMAP_BITS;
+
+ if (!bitmap)
+ return false;
+ return test_bit(bit, bitmap->bitmap);
+}
+EXPORT_SYMBOL(xb_test_bit);
+
+#ifndef __KERNEL__
+
+static DEFINE_XB(xb1);
+
+void xbitmap_check_bit(unsigned long bit)
+{
+ xb_preload(GFP_KERNEL);
+ assert(!xb_test_bit(&xb1, bit));
+ assert(xb_set_bit(&xb1, bit) == 0);
+ assert(xb_test_bit(&xb1, bit));
+ assert(xb_clear_bit(&xb1, bit) == 0);
+ assert(xb_empty(&xb1));
+ assert(xb_clear_bit(&xb1, bit) == 0);
+ assert(xb_empty(&xb1));
+ xb_preload_end();
+}
+
+void xbitmap_checks(void)
+{
+ xb_init(&xb1);
+ xbitmap_check_bit(0);
+ xbitmap_check_bit(30);
+ xbitmap_check_bit(31);
+ xbitmap_check_bit(1023);
+ xbitmap_check_bit(1024);
+ xbitmap_check_bit(1025);
+ xbitmap_check_bit((1UL << 63) | (1UL << 24));
+ xbitmap_check_bit((1UL << 63) | (1UL << 24) | 70);
+}
+
+int __weak main(void)
+{
+ radix_tree_init();
+ xbitmap_checks();
+}
+#endif
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index fa7ee36..34ece78 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -6,7 +6,8 @@ LDLIBS+= -lpthread -lurcu
TARGETS = main idr-test multiorder
CORE_OFILES := radix-tree.o idr.o linux.o test.o find_bit.o
OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
- tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
+ tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o \
+ xbitmap.o
ifndef SHIFT
SHIFT=3
@@ -25,8 +26,11 @@ idr-test: idr-test.o $(CORE_OFILES)
multiorder: multiorder.o $(CORE_OFILES)
+xbitmap: xbitmap.o $(CORE_OFILES)
+ $(CC) $(CFLAGS) $(LDFLAGS) $^ -o xbitmap
+
clean:
- $(RM) $(TARGETS) *.o radix-tree.c idr.c generated/map-shift.h
+ $(RM) $(TARGETS) *.o radix-tree.c idr.c xbitmap.c generated/map-shift.h
vpath %.c ../../lib
@@ -34,6 +38,7 @@ $(OFILES): Makefile *.h */*.h generated/map-shift.h \
../../include/linux/*.h \
../../include/asm/*.h \
../../../include/linux/radix-tree.h \
+ ../../../include/linux/xbitmap.h \
../../../include/linux/idr.h
radix-tree.c: ../../../lib/radix-tree.c
@@ -42,6 +47,9 @@ radix-tree.c: ../../../lib/radix-tree.c
idr.c: ../../../lib/idr.c
sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+xbitmap.c: ../../../lib/xbitmap.c
+ sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
.PHONY: mapshift
mapshift:
diff --git a/tools/testing/radix-tree/linux/xbitmap.h b/tools/testing/radix-tree/linux/xbitmap.h
new file mode 100644
index 0000000..61de214
--- /dev/null
+++ b/tools/testing/radix-tree/linux/xbitmap.h
@@ -0,0 +1 @@
+#include "../../../../include/linux/xbitmap.h"
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index 257f3f8..d112363 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -326,6 +326,10 @@ static void single_thread_tests(bool long_run)
rcu_barrier();
printv(2, "after idr_checks: %d allocated, preempt %d\n",
nr_allocated, preempt_count);
+ xbitmap_checks();
+ rcu_barrier();
+ printv(2, "after xbitmap_checks: %d allocated, preempt %d\n",
+ nr_allocated, preempt_count);
big_gang_check(long_run);
rcu_barrier();
printv(2, "after big_gang_check: %d allocated, preempt %d\n",
diff --git a/tools/testing/radix-tree/test.h b/tools/testing/radix-tree/test.h
index d9c031d..8175d6b 100644
--- a/tools/testing/radix-tree/test.h
+++ b/tools/testing/radix-tree/test.h
@@ -38,6 +38,7 @@ void benchmark(void);
void idr_checks(void);
void ida_checks(void);
void ida_thread_tests(void);
+void xbitmap_checks(void);
struct item *
item_tag_set(struct radix_tree_root *root, unsigned long index, int tag);
--
2.7.4
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