Messages in this thread |  | | Date | Wed, 1 Apr 2026 15:14:08 +0100 | | From | Pedro Falcato <> | | Subject | Re: [PATCH v2 0/2] mm/mprotect: micro-optimization work |
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On Wed, Apr 01, 2026 at 10:25:40AM +0200, David Hildenbrand (Arm) wrote: > On 3/30/26 22:06, Andrew Morton wrote: > > On Mon, 30 Mar 2026 15:55:51 -0400 Luke Yang <luyang@redhat.com> wrote: > > > >> Thanks for working on this. I just wanted to share that we've created a > >> test kernel with your patches and tested on the following CPUs: > >> > >> --- aarch64 --- > >> Ampere Altra > >> Ampere Altra Max > >> > >> --- x86_64 --- > >> AMD EPYC 7713 > >> AMD EPYC 7351 > >> AMD EPYC 7542 > >> AMD EPYC 7573X > >> AMD EPYC 7702 > >> AMD EPYC 9754 > >> Intel Xeon Gold 6126 > >> Into Xeon Gold 6330 > >> Intel Xeon Gold 6530 > >> Intel Xeon Platinum 8351N > >> Intel Core i7-6820HQ > >> > >> --- ppc64le --- > >> IBM Power 10 > >> > >> On average, we see improvements ranging from a minimum of 5% to a > >> maximum of 55%, with most improvements showing around a 25% speed up in > >> the libmicro/mprot_tw4m micro benchmark. > > > > Thanks, that's nice. I've added some of the above into the changelog > > and I took the liberty of adding your Tested-by: to both patches. > > > > fyi, regarding [2/2]: it's unclear to me whether the discussion with > > David will result in any alterations. If there's something I need to > > it always helps to lmk ;) > > I think we want to get a better understanding of which exact __always_inline > is really helpful in patch #2, and where to apply the nr_ptes==1 forced > optimization. > > I updated my microbenchmark I use for fork+unmap etc to measure > mprotect as well > > https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/pte-mapped-folio-benchmarks.c?ref_type=heads > > Running some simple tests with order-0 on 1 GiB of memory: > > > Upstream Linus: > > ./pte-mapped-folio-benchmarks 0 write-protect 5 > 0.005779 > ... > ./pte-mapped-folio-benchmarks 0 write-unprotect 5 > 0.009113 > ... > > > With Pedro's patch #2: > $ ./pte-mapped-folio-benchmarks 0 write-protect 5 > 0.003941 > ... > $ ./pte-mapped-folio-benchmarks 0 write-unprotect 5 > 0.006163 > ... > > > With the patch below: > > $ ./pte-mapped-folio-benchmarks 0 write-protect 5 > 0.003364 > > $ ./pte-mapped-folio-benchmarks 0 write-unprotect 5 > 0.005729
Hmm. Thanks for the testing. Interesting. I'll give it a shot. I'll have results and/or a possible v3 by tomorrow, if need be.
Apologies for the slight delay here! :)
-- Pedro
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