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charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 435A540003 X-Stat-Signature: 99a7oycdfouod7ojwkzuib4ydjcm47k9 X-Rspam-User: X-HE-Tag: 1723855599-250828 X-HE-Meta: U2FsdGVkX1/0fmhIggz3/iWldbBGYn9U3c6EA5KFc2mnyHQm4WQeqiaPl/hUpBbfML5DnIiQOSR6bvbjgICpZw0E4rQTtUicJLVlCCKM+5xh8uqu2lFewbTvqz67WFp/M0LlgVmPeTxcQP/pC7zuuxmWsKL8IY5oMccZLHgmyk0ftprrCyxzY3xO0BVcxCSTkbl7jBbJMDKFy5wVm50pQ9Yv77sAmDBxpum0KdS/nyY74q653yWDShqgs8B+ayRnvwo2z58dMG2QXsE2t1dxyDDleO0rUf0LznpSgq5+M60TrEMVldsOW1265oMvsA5a6mFMDyS2SI8OsD1WCdrcFm7S4iQbbC9XemayR/tg7awBigx9UZgnyXXuXBjE19kbohUkoIpUDcYYIoO5YmhY2WnXeufddQPnWXlstSTJe8aoLmXthV7rTYp7gV+gtWG8WBHRIU4Ba5B0fMz/dwRcvNLToSO+IkBhYHvFBKStUAaRTBg6OWBawsIcGDmLMCB76G+E/zI5HAIgjTj7nXX3l/Fu3wBvEKbtZiB1sYyJysz/wnOr2KL7f/unnaKmX9polN+2qE8CLe+vZ8QyfhOFar/Q0eJeYhg+ecC17YwgeYYFlYvRl0QvkPe7rAXPWDUieDkIpv1euQn6+bsWsUdPYWCOxr5GZdAScr1pUfq5XVgQS3DUdumReJ23ye/j+NflcMUbHTOtbfJIn+6xCUzy+YDeAdJL8XrXEhZYBB8chRSyIUJ/QmuRJo3Of+DnpE4jYWFhH2lIDdFC4eMMzF+fCjn9LFMMLouOJf5WHr22VTMuQZ0sIiG1nGinbX3oy3Y/VLUbeedWgOGSRvtzkubJZZBI8ELETHgH06LZCO2RlurrGJQIoa4LlMgH68jCKzfUOl+sS5GkTT+sweB0jo2J7LusYqxCcxI0smRyGWgFFJ/ZdKo+aFVktLd3IuEo5zQEyrndWcM4Kh4PYmwyVFQ mk9dHWgv 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 25, 2024, James Houghton wrote: > On Tue, Jul 23, 2024 at 6:11=E2=80=AFPM James Houghton wrote: > > > > Replace the MMU write locks (taken in the memslot iteration loop) for > > read locks. > > > > Grabbing the read lock instead of the write lock is safe because the > > only requirement we have is that the stage-2 page tables do not get > > deallocated while we are walking them. The stage2_age_walker() callback > > is safe to race with itself; update the comment to reflect the > > synchronization change. > > > > Signed-off-by: James Houghton > > --- >=20 > Here is some data to show that this patch at least *can* be helpful: >=20 > # arm64 patched to do aging (i.e., set HAVE_KVM_MMU_NOTIFIER_YOUNG_FAST_O= NLY) > # The test is faulting memory in while doing aging as fast as possible. > # taskset -c 0-32 ./access_tracking_perf_test -l -r /dev/cgroup/memory > -p -v 32 -m 3 >=20 > # Write lock > vcpu wall time : 3.039207157s > lru_gen avg pass duration : 1.660541541s, (passes:2, total:3.32108308= 3s) >=20 > # Read lock > vcpu wall time : 3.010848445s > lru_gen avg pass duration : 0.306623698s, (passes:11, total:3.3728606= 88s) >=20 > Aging is able to run significantly faster, but vCPU runtime isn't > affected much (in this test). Were you expecting vCPU runtime to improve (more)? If so, lack of movement= could be due to KVM arm64 taking mmap_lock for read when handling faults: https://lore.kernel.org/all/Zr0ZbPQHVNzmvwa6@google.com