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Date: Fri, 22 Jan 2021 08:55:31 +0800 From: Chao Yu <yuchao0@...wei.com> To: Daeho Jeong <daeho43@...il.com>, <linux-kernel@...r.kernel.org>, <linux-f2fs-devel@...ts.sourceforge.net>, <kernel-team@...roid.com> CC: Sungjong Seo <sj1557.seo@...sung.com>, Daeho Jeong <daehojeong@...gle.com> Subject: Re: [f2fs-dev] [PATCH v5 1/2] f2fs: introduce checkpoint=merge mount option If there is no update in v5, it will be better to include my Reviewed-by tag, please note that. :) Thanks, On 2021/1/21 21:45, Daeho Jeong wrote: > From: Daeho Jeong<daehojeong@...gle.com> > > We've added a new mount option "checkpoint=merge", which creates a > kernel daemon and makes it to merge concurrent checkpoint requests as > much as possible to eliminate redundant checkpoint issues. Plus, we > can eliminate the sluggish issue caused by slow checkpoint operation > when the checkpoint is done in a process context in a cgroup having > low i/o budget and cpu shares. To make this do better, we set the > default i/o priority of the kernel daemon to "3", to give one higher > priority than other kernel threads. The below verification result > explains this. > The basic idea has come fromhttps://opensource.samsung.com. > > [Verification] > Android Pixel Device(ARM64, 7GB RAM, 256GB UFS) > Create two I/O cgroups (fg w/ weight 100, bg w/ wight 20) > Set "strict_guarantees" to "1" in BFQ tunables > > In "fg" cgroup, > - thread A => trigger 1000 checkpoint operations > "for i in `seq 1 1000`; do touch test_dir1/file; fsync test_dir1; > done" > - thread B => gererating async. I/O > "fio --rw=write --numjobs=1 --bs=128k --runtime=3600 --time_based=1 > --filename=test_img --name=test" > > In "bg" cgroup, > - thread C => trigger repeated checkpoint operations > "echo $$ > /dev/blkio/bg/tasks; while true; do touch test_dir2/file; > fsync test_dir2; done" > > We've measured thread A's execution time. > > [ w/o patch ] > Elapsed Time: Avg. 68 seconds > [ w/ patch ] > Elapsed Time: Avg. 48 seconds > > Signed-off-by: Daeho Jeong<daehojeong@...gle.com> > Signed-off-by: Sungjong Seo<sj1557.seo@...sung.com>
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