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charset="UTF-8" Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=VTTDGHlS; spf=pass (imf28.hostedemail.com: domain of hsinyi@chromium.org designates 209.85.166.45 as permitted sender) smtp.mailfrom=hsinyi@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 26885900185D X-Stat-Signature: 4awm7h5fad3r8igrgoqbh51ykcocaez5 X-HE-Tag: 1633525703-518587 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000553, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Oct 6, 2021 at 7:21 PM Matthew Wilcox wrote: > > On Wed, Oct 06, 2021 at 05:25:23PM +0800, Hsin-Yi Wang wrote: > > Hi Matthew, > > > > We tested that the performance of readahead is regressed on multicore > > arm64 platforms running on the 5.10 kernel. > > - The platform we used: 8 cores (4x a53(small), 4x a73(big)) arm64 platform > > - The command we used: ureadahead $FILE ($FILE is a 1MB+ pack file, > > note that if the file size is small, it's not obvious to see the > > regression) > > > > After we revert the commit c1f6925e1091("mm: put readahead pages in > > cache earlier"), the readahead performance is back: > > - time ureadahead $FILE: > > - 5.10: 1m23.124s > > - with c1f6925e1091 reverted: 0m3.323s > > - other LTS kernel (eg. 5.4): 0m3.066s > > > > The slowest part is aops->readpage() in read_pages() called in > > read_pages(ractl, &page_pool, false); (the 3rd in > > page_cache_ra_unbounded()) > > What filesystem are you using? > ext4, block size 4096