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.
