From: "Christian König" <christian.koenig@amd.com>
To: Christoph Hellwig <hch@infradead.org>,
John Stultz <john.stultz@linaro.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Daniel Vetter <daniel@ffwll.ch>,
Sumit Semwal <sumit.semwal@linaro.org>,
Liam Mark <lmark@codeaurora.org>,
Chris Goldsworthy <cgoldswo@codeaurora.org>,
Laura Abbott <labbott@kernel.org>,
Brian Starkey <Brian.Starkey@arm.com>,
Hridya Valsaraju <hridya@google.com>,
Suren Baghdasaryan <surenb@google.com>,
Sandeep Patil <sspatil@google.com>,
Daniel Mentz <danielmentz@google.com>,
??rjan Eide <orjan.eide@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Ezequiel Garcia <ezequiel@collabora.com>,
Simon Ser <contact@emersion.fr>, James Jones <jajones@nvidia.com>,
linux-media <linux-media@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Mel Gorman <mgorman@suse.de>, linux-mm <linux-mm@kvack.org>
Subject: Re: page pools, was Re: [PATCH v9 1/5] drm: Add a sharable drm page-pool implementation
Date: Thu, 8 Jul 2021 09:37:41 +0200 [thread overview]
Message-ID: <798f5d1d-b64c-8c73-bfe6-701893820ff0@amd.com> (raw)
In-Reply-To: <YOZ9JZlwkjyDGti5@infradead.org>
Am 08.07.21 um 06:20 schrieb Christoph Hellwig:
> On Wed, Jul 07, 2021 at 12:35:23PM -0700, John Stultz wrote:
>> So, as Christian mentioned, on the TTM side it's useful, as they are
>> trying to avoid TLB flushes when changing caching attributes.
>>
>> For the dmabuf system heap purposes, the main benefit is moving the
>> page zeroing to the free path, rather than the allocation path. This
>> on its own doesn't save much, but allows us to defer frees (and thus
>> the zeroing) to the background, which can get that work out of the hot
>> path.
> I really do no think that is worth it to fragment the free pages.
And I think functionality like that should be part of the common page
allocator.
I mean we already have __GFP_ZERO, why not have a background kernel
thread which zeros free pages when a CPU core is idle? (I'm pretty sure
we already have that somehow).
Christian.
WARNING: multiple messages have this Message-ID (diff)
From: "Christian König" <christian.koenig@amd.com>
To: Christoph Hellwig <hch@infradead.org>,
John Stultz <john.stultz@linaro.org>
Cc: dri-devel <dri-devel@lists.freedesktop.org>,
Sandeep Patil <sspatil@google.com>, linux-mm <linux-mm@kvack.org>,
Ezequiel Garcia <ezequiel@collabora.com>,
Robin Murphy <robin.murphy@arm.com>,
James Jones <jajones@nvidia.com>,
lkml <linux-kernel@vger.kernel.org>,
Liam Mark <lmark@codeaurora.org>, Mel Gorman <mgorman@suse.de>,
Laura Abbott <labbott@kernel.org>,
Chris Goldsworthy <cgoldswo@codeaurora.org>,
Hridya Valsaraju <hridya@google.com>,
??rjan Eide <orjan.eide@arm.com>,
linux-media <linux-media@vger.kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Daniel Mentz <danielmentz@google.com>
Subject: Re: page pools, was Re: [PATCH v9 1/5] drm: Add a sharable drm page-pool implementation
Date: Thu, 8 Jul 2021 09:37:41 +0200 [thread overview]
Message-ID: <798f5d1d-b64c-8c73-bfe6-701893820ff0@amd.com> (raw)
In-Reply-To: <YOZ9JZlwkjyDGti5@infradead.org>
Am 08.07.21 um 06:20 schrieb Christoph Hellwig:
> On Wed, Jul 07, 2021 at 12:35:23PM -0700, John Stultz wrote:
>> So, as Christian mentioned, on the TTM side it's useful, as they are
>> trying to avoid TLB flushes when changing caching attributes.
>>
>> For the dmabuf system heap purposes, the main benefit is moving the
>> page zeroing to the free path, rather than the allocation path. This
>> on its own doesn't save much, but allows us to defer frees (and thus
>> the zeroing) to the background, which can get that work out of the hot
>> path.
> I really do no think that is worth it to fragment the free pages.
And I think functionality like that should be part of the common page
allocator.
I mean we already have __GFP_ZERO, why not have a background kernel
thread which zeros free pages when a CPU core is idle? (I'm pretty sure
we already have that somehow).
Christian.
next prev parent reply other threads:[~2021-07-08 7:38 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-30 1:34 [PATCH v9 0/5] Generic page pool & deferred freeing for system dmabuf hea John Stultz
2021-06-30 1:34 ` John Stultz
2021-06-30 1:34 ` [PATCH v9 1/5] drm: Add a sharable drm page-pool implementation John Stultz
2021-06-30 1:34 ` John Stultz
2021-06-30 9:10 ` Christian König
2021-06-30 9:10 ` Christian König
2021-06-30 22:24 ` John Stultz
2021-06-30 22:24 ` John Stultz
2021-07-01 6:52 ` Christian König
2021-07-01 6:52 ` Christian König
2021-07-06 21:03 ` John Stultz
2021-07-06 21:03 ` John Stultz
2021-07-06 21:15 ` Daniel Vetter
2021-07-06 21:15 ` Daniel Vetter
2021-07-06 21:19 ` John Stultz
2021-07-06 21:19 ` John Stultz
2021-07-07 6:52 ` Christian König
2021-07-07 6:52 ` Christian König
2021-07-07 6:38 ` page pools, was " Christoph Hellwig
2021-07-07 7:10 ` Christian König
2021-07-07 7:10 ` Christian König
2021-07-07 7:14 ` Christoph Hellwig
2021-07-07 9:32 ` Christian König
2021-07-07 9:32 ` Christian König
2021-07-07 19:42 ` John Stultz
2021-07-07 19:42 ` John Stultz
2021-07-07 19:42 ` John Stultz
2021-07-07 19:35 ` John Stultz
2021-07-07 19:35 ` John Stultz
2021-07-07 19:35 ` John Stultz
2021-07-08 4:20 ` Christoph Hellwig
2021-07-08 7:37 ` Christian König [this message]
2021-07-08 7:37 ` Christian König
2021-06-30 1:34 ` [PATCH v9 2/5] drm: ttm_pool: Rework ttm_pool to use drm_page_pool John Stultz
2021-06-30 1:34 ` John Stultz
2021-06-30 5:11 ` kernel test robot
2021-06-30 5:11 ` kernel test robot
2021-06-30 1:34 ` [PATCH v9 3/5] dma-buf: system_heap: Add drm pagepool support to system heap John Stultz
2021-06-30 1:34 ` John Stultz
2021-06-30 4:34 ` kernel test robot
2021-06-30 4:34 ` kernel test robot
2021-06-30 5:25 ` kernel test robot
2021-06-30 5:25 ` kernel test robot
2021-06-30 1:34 ` [PATCH v9 4/5] dma-buf: heaps: Add deferred-free-helper library code John Stultz
2021-06-30 1:34 ` John Stultz
2021-06-30 1:34 ` [PATCH v9 5/5] dma-buf: system_heap: Add deferred freeing to the system heap John Stultz
2021-06-30 1:34 ` John Stultz
2021-06-30 9:13 ` [PATCH v9 0/5] Generic page pool & deferred freeing for system dmabuf hea Christian König
2021-06-30 9:13 ` Christian König
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