On Wed, Mar 27, 2019 at 09:08:21AM +0100, Christoph Hellwig wrote: > On Tue, Mar 26, 2019 at 04:01:26PM -0700, Nicolin Chen wrote: > > This series of patches try to save single pages from CMA area bypassing > > all CMA single page alloctions and allocating normal pages instead, as > > all addresses within one single page are contiguous. > > > > We had once applied the PATCH-5 but reverted it as actually not all the > > callers handled the fallback allocations. Per Robin's suggestion, let's > > stuff alloc_pages()/free_page() fallbacks to those callers before having > > PATCH-5. > > Given the problems this has caused so far I'd like to see a good > explanation of why this optimization is so important that all the churn > is even worth it..
With certain downstream user cases, we had run into a CMA exhaustion situation, and this was one of the changes that eased the problem. I have all the reasoning in the PATCH-5 commit message. And what Robin tested can also justify for it: https://lore.kernel.org/patchwork/patch/1004934/#1190139 Thanks _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
