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SubjectRe: page pools, was Re: [PATCH v9 1/5] drm: Add a sharable drm page-pool implementation
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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.

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