From: Wei Wang <wei.w.wang@intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
virtualization@lists.linux-foundation.org, mst@redhat.com,
mawilcox@microsoft.com, dave.hansen@intel.com,
akpm@linux-foundation.org, zhenwei.pi@youruncloud.com
Subject: Re: [PATCH] mm: don't zero ballooned pages
Date: Mon, 31 Jul 2017 15:41:49 +0800 [thread overview]
Message-ID: <597EDF3D.8020101@intel.com> (raw)
In-Reply-To: <20170731065508.GE13036@dhcp22.suse.cz>
On 07/31/2017 02:55 PM, Michal Hocko wrote:
> On Mon 31-07-17 12:13:33, Wei Wang wrote:
>> Ballooned pages will be marked as MADV_DONTNEED by the hypervisor and
>> shouldn't be given to the host ksmd to scan.
> Could you point me where this MADV_DONTNEED is done, please?
Sure. It's done in the hypervisor when the balloon pages are received.
Please see line 40 at
https://github.com/qemu/qemu/blob/master/hw/virtio/virtio-balloon.c
>
>> Therefore, it is not
>> necessary to zero ballooned pages, which is very time consuming when
>> the page amount is large. The ongoing fast balloon tests show that the
>> time to balloon 7G pages is increased from ~491ms to 2.8 seconds with
>> __GFP_ZERO added. So, this patch removes the flag.
> Please make it obvious that this is a revert of bb01b64cfab7
> ("mm/balloon_compaction.c: enqueue zero page to balloon device").
>
>
Ok, will do.
Best,
Wei
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WARNING: multiple messages have this Message-ID (diff)
From: Wei Wang <wei.w.wang@intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
virtualization@lists.linux-foundation.org, mst@redhat.com,
mawilcox@microsoft.com, dave.hansen@intel.com,
akpm@linux-foundation.org, zhenwei.pi@youruncloud.com
Subject: Re: [PATCH] mm: don't zero ballooned pages
Date: Mon, 31 Jul 2017 15:41:49 +0800 [thread overview]
Message-ID: <597EDF3D.8020101@intel.com> (raw)
In-Reply-To: <20170731065508.GE13036@dhcp22.suse.cz>
On 07/31/2017 02:55 PM, Michal Hocko wrote:
> On Mon 31-07-17 12:13:33, Wei Wang wrote:
>> Ballooned pages will be marked as MADV_DONTNEED by the hypervisor and
>> shouldn't be given to the host ksmd to scan.
> Could you point me where this MADV_DONTNEED is done, please?
Sure. It's done in the hypervisor when the balloon pages are received.
Please see line 40 at
https://github.com/qemu/qemu/blob/master/hw/virtio/virtio-balloon.c
>
>> Therefore, it is not
>> necessary to zero ballooned pages, which is very time consuming when
>> the page amount is large. The ongoing fast balloon tests show that the
>> time to balloon 7G pages is increased from ~491ms to 2.8 seconds with
>> __GFP_ZERO added. So, this patch removes the flag.
> Please make it obvious that this is a revert of bb01b64cfab7
> ("mm/balloon_compaction.c: enqueue zero page to balloon device").
>
>
Ok, will do.
Best,
Wei
next prev parent reply other threads:[~2017-07-31 7:39 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-31 4:13 [PATCH] mm: don't zero ballooned pages Wei Wang
2017-07-31 4:13 ` Wei Wang
2017-07-31 6:55 ` Michal Hocko
2017-07-31 6:55 ` Michal Hocko
2017-07-31 6:55 ` Michal Hocko
2017-07-31 7:39 ` ZhenweiPi
2017-07-31 7:39 ` ZhenweiPi
2017-07-31 7:39 ` ZhenweiPi
2017-07-31 7:41 ` Wei Wang
2017-07-31 7:41 ` Wei Wang [this message]
2017-07-31 7:41 ` Wei Wang
2017-07-31 7:43 ` Michal Hocko
2017-07-31 7:43 ` Michal Hocko
2017-07-31 7:43 ` Michal Hocko
2017-07-31 8:34 ` Wei Wang
2017-07-31 8:34 ` Wei Wang
2017-07-31 8:34 ` Wei Wang
2017-07-31 7:51 ` Michal Hocko
2017-07-31 7:51 ` Michal Hocko
2017-07-31 8:23 ` ZhenweiPi
2017-07-31 8:37 ` Michal Hocko
2017-07-31 8:37 ` Michal Hocko
2017-07-31 8:37 ` Michal Hocko
2017-08-01 15:38 ` Michael S. Tsirkin
2017-08-01 15:38 ` Michael S. Tsirkin
2017-08-01 15:38 ` Michael S. Tsirkin
2017-07-31 8:23 ` ZhenweiPi
2017-07-31 7:51 ` Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2017-07-31 4:13 Wei Wang
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