[PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Jens Axboe]

Nobody is maintaining this code, and it just falls under the umbrella
of block layer code. But at least mark it as such, in case anyone wants
to care more deeply about it and assume the responsibility of doing so.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/MAINTAINERS b/MAINTAINERS
index 42decde38320..4a857a125d6e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3781,10 +3781,8 @@ F:	Documentation/filesystems/befs.rst
 F:	fs/befs/
 
 BFQ I/O SCHEDULER
-M:	Paolo Valente <paolo.valente@unimore.it>
-M:	Jens Axboe <axboe@kernel.dk>
 L:	linux-block@vger.kernel.org
-S:	Maintained
+S:	Orphan
 F:	Documentation/block/bfq-iosched.rst
 F:	block/bfq-*
 
-- 
Jens Axboe

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Bart Van Assche]

On 9/3/24 8:53 AM, Jens Axboe wrote:
> Nobody is maintaining this code, and it just falls under the umbrella
> of block layer code. But at least mark it as such, in case anyone wants
> to care more deeply about it and assume the responsibility of doing so.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> ---
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 42decde38320..4a857a125d6e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3781,10 +3781,8 @@ F:	Documentation/filesystems/befs.rst
>   F:	fs/befs/
>   
>   BFQ I/O SCHEDULER
> -M:	Paolo Valente <paolo.valente@unimore.it>
> -M:	Jens Axboe <axboe@kernel.dk>
>   L:	linux-block@vger.kernel.org
> -S:	Maintained
> +S:	Orphan
>   F:	Documentation/block/bfq-iosched.rst
>   F:	block/bfq-*
>   

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Bart Van Assche]

On 9/3/24 8:53 AM, Jens Axboe wrote:
> Nobody is maintaining this code, and it just falls under the umbrella
> of block layer code. But at least mark it as such, in case anyone wants
> to care more deeply about it and assume the responsibility of doing so.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> ---
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 42decde38320..4a857a125d6e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3781,10 +3781,8 @@ F:	Documentation/filesystems/befs.rst
>   F:	fs/befs/
>   
>   BFQ I/O SCHEDULER
> -M:	Paolo Valente <paolo.valente@unimore.it>
> -M:	Jens Axboe <axboe@kernel.dk>
>   L:	linux-block@vger.kernel.org
> -S:	Maintained
> +S:	Orphan
>   F:	Documentation/block/bfq-iosched.rst
>   F:	block/bfq-*

To the memstick and mmc maintainers, should the Kconfig files for these
drivers perhaps be updated? This is what I found by searching for
IOSCHED_BFQ:

$ git grep -nH 'imply.*BFQ'
drivers/memstick/core/Kconfig:23:	imply IOSCHED_BFQ
drivers/memstick/core/Kconfig:33:	imply IOSCHED_BFQ
drivers/mmc/core/Kconfig:40:	imply IOSCHED_BFQ

Thanks,

Bart.

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Ulf Hansson]

On Tue, 3 Sept 2024 at 17:54, Jens Axboe <axboe@kernel.dk> wrote:
>
> Nobody is maintaining this code, and it just falls under the umbrella
> of block layer code. But at least mark it as such, in case anyone wants
> to care more deeply about it and assume the responsibility of doing so.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

I haven't spoken to Paolo recently (just dropped him an email), but I
was under the impression that he intended to keep an eye on the BFQ
scheduler.

BTW, why didn't you cc him?

Kind regards
Uffe


>
> ---
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 42decde38320..4a857a125d6e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3781,10 +3781,8 @@ F:       Documentation/filesystems/befs.rst
>  F:     fs/befs/
>
>  BFQ I/O SCHEDULER
> -M:     Paolo Valente <paolo.valente@unimore.it>
> -M:     Jens Axboe <axboe@kernel.dk>
>  L:     linux-block@vger.kernel.org
> -S:     Maintained
> +S:     Orphan
>  F:     Documentation/block/bfq-iosched.rst
>  F:     block/bfq-*
>
> --
> Jens Axboe
>
>

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Jens Axboe]

On 9/4/24 7:27 AM, Ulf Hansson wrote:
> On Tue, 3 Sept 2024 at 17:54, Jens Axboe <axboe@kernel.dk> wrote:
>>
>> Nobody is maintaining this code, and it just falls under the umbrella
>> of block layer code. But at least mark it as such, in case anyone wants
>> to care more deeply about it and assume the responsibility of doing so.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> I haven't spoken to Paolo recently (just dropped him an email), but I
> was under the impression that he intended to keep an eye on the BFQ
> scheduler.

But he hasn't, it's been a long time since he was involved. I've been
applying patches on an as-needed basis, but effectively nobody has
been maintaining it for probably 2 years at this point.

> BTW, why didn't you cc him?

That was an oversight, I think because I haven't seen anything from
him in a long time to assumed he was awol.

-- 
Jens Axboe

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Ulf Hansson]

+ Paolo

On Wed, 4 Sept 2024 at 15:47, Jens Axboe <axboe@kernel.dk> wrote:
>
> On 9/4/24 7:27 AM, Ulf Hansson wrote:
> > On Tue, 3 Sept 2024 at 17:54, Jens Axboe <axboe@kernel.dk> wrote:
> >>
> >> Nobody is maintaining this code, and it just falls under the umbrella
> >> of block layer code. But at least mark it as such, in case anyone wants
> >> to care more deeply about it and assume the responsibility of doing so.
> >>
> >> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> >
> > I haven't spoken to Paolo recently (just dropped him an email), but I
> > was under the impression that he intended to keep an eye on the BFQ
> > scheduler.
>
> But he hasn't, it's been a long time since he was involved. I've been
> applying patches on an as-needed basis, but effectively nobody has
> been maintaining it for probably 2 years at this point.

I don't think we should expect him to do active development, but
rather just to keep an eye on it from maintenance point of view.

Let me try to get in contact with him for an update.

>
> > BTW, why didn't you cc him?
>
> That was an oversight, I think because I haven't seen anything from
> him in a long time to assumed he was awol.

I looked at the last year or so at the linux-block mailing-list and it
seems most patches for bfq aren't being sent to his email. :-(

Ohh well, let's see what we can do about this. Surely BFQ is being
used out there, so it would really be a pity if nobody takes good care
of it.

Kind regards
Uffe

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Jens Axboe]

On 9/4/24 7:59 AM, Ulf Hansson wrote:
> + Paolo
> 
> On Wed, 4 Sept 2024 at 15:47, Jens Axboe <axboe@kernel.dk> wrote:
>>
>> On 9/4/24 7:27 AM, Ulf Hansson wrote:
>>> On Tue, 3 Sept 2024 at 17:54, Jens Axboe <axboe@kernel.dk> wrote:
>>>>
>>>> Nobody is maintaining this code, and it just falls under the umbrella
>>>> of block layer code. But at least mark it as such, in case anyone wants
>>>> to care more deeply about it and assume the responsibility of doing so.
>>>>
>>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>>
>>> I haven't spoken to Paolo recently (just dropped him an email), but I
>>> was under the impression that he intended to keep an eye on the BFQ
>>> scheduler.
>>
>> But he hasn't, it's been a long time since he was involved. I've been
>> applying patches on an as-needed basis, but effectively nobody has
>> been maintaining it for probably 2 years at this point.
> 
> I don't think we should expect him to do active development, but
> rather just to keep an eye on it from maintenance point of view.

I never expect active development, there may not be a need for it. But
basic maintenance is definitely the maintainers role. As that hasn't
been happening for quite a while, I'd consider it orphaned.

>>> BTW, why didn't you cc him?
>>
>> That was an oversight, I think because I haven't seen anything from
>> him in a long time to assumed he was awol.
> 
> I looked at the last year or so at the linux-block mailing-list and it
> seems most patches for bfq aren't being sent to his email. :-(
> 
> Ohh well, let's see what we can do about this. Surely BFQ is being
> used out there, so it would really be a pity if nobody takes good care
> of it.

Probably not a whole lot I think, at least on the prod side experiences
with BFQ haven't been good. So there's definitely fixes to do, and I was
happy to see fixes being sent in recently to address some concerns.
Someone with actual customers using it and finding issues, or someone
actually using it.

-- 
Jens Axboe

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Linus Walleij]

On Wed, Sep 4, 2024 at 4:07 PM Jens Axboe <axboe@kernel.dk> wrote:
> On 9/4/24 7:59 AM, Ulf Hansson wrote:

>>  Surely BFQ is being
> > used out there, so it would really be a pity if nobody takes good care
> > of it.
>
> Probably not a whole lot I think, at least on the prod side experiences
> with BFQ haven't been good.

Which production? For singlequeue devices it is pretty widespread.

It is used in Fedora, RedHat and SuSE as default scheduler for any
/dev/sdN, /dev/srN and /dev/mmcblkN (i.e. anything singlequeue).

Example from my main development machine with Fedora 40:
$ cat /sys/block/sda/queue/scheduler
none mq-deadline kyber [bfq]
Laptop with MMC card reader:
$ cat /sys/block/mmcblk0/queue/scheduler
none mq-deadline kyber [bfq]

Maybe we should propose these rules to the main udev repository
so that they also go into Debian and we get even wider use?

It is also used by default in all Chromebooks using eMMC as storage.
I think even all Android devices using eMMC is using it but that is
hard to check.

Yours,
Linus Walleij

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Jens Axboe]

On 9/5/24 7:03 AM, Linus Walleij wrote:
> On Wed, Sep 4, 2024 at 4:07?PM Jens Axboe <axboe@kernel.dk> wrote:
>> On 9/4/24 7:59 AM, Ulf Hansson wrote:
> 
>>>  Surely BFQ is being
>>> used out there, so it would really be a pity if nobody takes good care
>>> of it.
>>
>> Probably not a whole lot I think, at least on the prod side experiences
>> with BFQ haven't been good.
> 
> Which production? For singlequeue devices it is pretty widespread.

We tried it at one point internally at Meta, and it was not pretty. Now
it's just disabled so people don't inadvertently pick it (as some people
like to do when fiddling with things).

> It is used in Fedora, RedHat and SuSE as default scheduler for any
> /dev/sdN, /dev/srN and /dev/mmcblkN (i.e. anything singlequeue).
> 
> Example from my main development machine with Fedora 40:
> $ cat /sys/block/sda/queue/scheduler
> none mq-deadline kyber [bfq]
> Laptop with MMC card reader:
> $ cat /sys/block/mmcblk0/queue/scheduler
> none mq-deadline kyber [bfq]
> 
> Maybe we should propose these rules to the main udev repository
> so that they also go into Debian and we get even wider use?

I know you like to push for it to be the default, and I always push back
because I don't think it's stable enough for that, and now we have the
added complication that it hasn't been maintained for quite a while.
So no, I don't think so.

There are some bugzilla entries too that never got resolved or moved
very far. Some of those may now be invalid, maybe not. Impossible to
know.

-- 
Jens Axboe

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Linus Walleij]

On Thu, Sep 5, 2024 at 4:58 PM Jens Axboe <axboe@kernel.dk> wrote:
> On 9/5/24 7:03 AM, Linus Walleij wrote:

> > Which production? For singlequeue devices it is pretty widespread.
>
> We tried it at one point internally at Meta, and it was not pretty.

I didn't know you used any singlequeue devices.

If you used it on multiqueue devices, well that can't be recommended.

> > Maybe we should propose these rules to the main udev repository
> > so that they also go into Debian and we get even wider use?
>
> I know you like to push for it to be the default, and I always push back
> because I don't think it's stable enough for that, and now we have the
> added complication that it hasn't been maintained for quite a while.
> So no, I don't think so.

The reason I like it personally is that it has actually saved me from
crashing my machine by preserving interactivity on a (single queue)
device:
https://people.kernel.org/linusw/bfq-saved-me-from-thrashing

For Androids and chromebooks it keeps the device interactive
during heavy disk (eMMC) activity, such as when Android
updates a pile of apps (.apk files).

> There are some bugzilla entries too that never got resolved or moved
> very far. Some of those may now be invalid, maybe not. Impossible to
> know.

OK fair enough, I hear there is a maintainer that will look after
it now.

Yours,
Linus Walleij

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Bart Van Assche]

On 9/5/24 11:05 AM, Linus Walleij wrote:
> For Androids and chromebooks it keeps the device interactive
> during heavy disk (eMMC) activity, such as when Android
> updates a pile of apps (.apk files).
  Is that issue perhaps specific to eMMC devices? I have never seen
an Android device with UFS storage becoming unresponsive during app
updates. Additionally, now that the mq-deadline I/O scheduler supports
I/O priorities, it is easy to give foreground I/O a higher priority in
Android than background I/O. All that is needed is to add something like
the following in an .rc file that is executed during boot:

write /dev/blkio/blkio.prio.class promote-to-rt

Bart.

Re: [PATCH] MAINTAINERS: move the BFQ io scheduler to orphan state

[Jens Axboe]

On 9/5/24 12:05 PM, Linus Walleij wrote:
> On Thu, Sep 5, 2024 at 4:58?PM Jens Axboe <axboe@kernel.dk> wrote:
>> On 9/5/24 7:03 AM, Linus Walleij wrote:
> 
>>> Which production? For singlequeue devices it is pretty widespread.
>>
>> We tried it at one point internally at Meta, and it was not pretty.
> 
> I didn't know you used any singlequeue devices.
> 
> If you used it on multiqueue devices, well that can't be recommended.

Of course we have single queue devices, anything that isn't nvme is
basically single queue.

>>> Maybe we should propose these rules to the main udev repository
>>> so that they also go into Debian and we get even wider use?
>>
>> I know you like to push for it to be the default, and I always push back
>> because I don't think it's stable enough for that, and now we have the
>> added complication that it hasn't been maintained for quite a while.
>> So no, I don't think so.
> 
> The reason I like it personally is that it has actually saved me from
> crashing my machine by preserving interactivity on a (single queue)
> device:
> https://people.kernel.org/linusw/bfq-saved-me-from-thrashing

I'd consider that largely anecdotal at this point.

> For Androids and chromebooks it keeps the device interactive
> during heavy disk (eMMC) activity, such as when Android
> updates a pile of apps (.apk files).

I'm somewhat dubious that that problem could not be solved in a much
simpler way than what is BFQ.

-- 
Jens Axboe