On Thu, Jan 06, 2011 at 06:10:06AM +0800, Andrew Morton wrote: > On Wed, 05 Jan 2011 16:00:09 +0800 > Shaohua Li <shaohua.li@xxxxxxxxx> wrote: > > > The zone->lru_lock is heavily contented in workload where activate_page() > > is frequently used. We could do batch activate_page() to reduce the lock > > contention. The batched pages will be added into zone list when the pool > > is full or page reclaim is trying to drain them. > > > > For example, in a 4 socket 64 CPU system, create a sparse file and 64 processes, > > processes shared map to the file. Each process read access the whole file and > > then exit. The process exit will do unmap_vmas() and cause a lot of > > activate_page() call. In such workload, we saw about 58% total time reduction > > with below patch. Other workloads with a lot of activate_page also benefits a > > lot too. > > There still isn't much info about the performance benefit here. Which > is a bit of a problem when the patch's sole purpose is to provide > performance benefit! > > So, much more complete performance testing results would help here. > And it's not just the "it sped up an obscure corner-case workload by > N%". How much impact (postive or negative) does the patch have on > other workloads? > > And while you're doing the performance testing, please test this > version too: I tested some microbenchmarks: case-anon-cow-rand-mt 0.58% case-anon-cow-rand -3.30% case-anon-cow-seq-mt -0.51% case-anon-cow-seq -5.68% case-anon-r-rand-mt 0.23% case-anon-r-rand 0.81% case-anon-r-seq-mt -0.71% case-anon-r-seq -1.99% case-anon-rx-rand-mt 2.11% case-anon-rx-seq-mt 3.46% case-anon-w-rand-mt -0.03% case-anon-w-rand -0.50% case-anon-w-seq-mt -1.08% case-anon-w-seq -0.12% case-anon-wx-rand-mt -5.02% case-anon-wx-seq-mt -1.43% case-fork 1.65% case-fork-sleep -0.07% case-fork-withmem 1.39% case-hugetlb -0.59% case-lru-file-mmap-read-mt -0.54% case-lru-file-mmap-read 0.61% case-lru-file-mmap-read-rand -2.24% case-lru-file-readonce -0.64% case-lru-file-readtwice -11.69% case-lru-memcg -1.35% case-mmap-pread-rand-mt 1.88% case-mmap-pread-rand -15.26% case-mmap-pread-seq-mt 0.89% case-mmap-pread-seq -69.72% case-mmap-xread-rand-mt 0.71% case-mmap-xread-seq-mt 0.38% The most significent are: case-lru-file-readtwice -11.69% case-mmap-pread-rand -15.26% case-mmap-pread-seq -69.72% which use activate_page a lot. others are basically variations because each run has slightly difference. Your patch doesn't change anything. I tried postmark too, nothing significant. Also I tried about 20 ffsb cases and 40 fio cases in two other machines, no big difference too. Thanks, Shaohua -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>