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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.


      reply	other threads:[~2021-07-08  8:10 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210630013421.735092-1-john.stultz@linaro.org>
     [not found] ` <20210630013421.735092-2-john.stultz@linaro.org>
2021-07-07  6:38   ` Christoph Hellwig
2021-07-07  7:10     ` Christian König
2021-07-07  7:14       ` Christoph Hellwig
2021-07-07  9:32         ` Christian König
2021-07-07 19:42         ` 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]

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