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charset=us-ascii Content-Disposition: inline In-Reply-To: <0145f5db-1adf-46d1-1a2e-41230ab1e462@huawei.com> X-Stat-Signature: 9bprf98boxtuz44r5hn83fubacfjttpd X-Rspamd-Queue-Id: 8CAD91C0002 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1713934281-885907 X-HE-Meta: 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 ck5PoF22 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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: Hi Peng, On Wed, Apr 24, 2024 at 12:29:25PM +0800, zhangpeng (AS) wrote: > On 2024/4/18 22:20, Peng Zhang wrote: > > Any suggestions or opinions are welcome. Could someone please review > this patch series? > Thanks! > Sorry, I haven't been very active lately. This is what I remember discussing a while back. I'll take a close look tomorrow. Thanks, Dennis > > From: ZhangPeng > > > > Since commit f1a7941243c1 ("mm: convert mm's rss stats into > > percpu_counter"), the rss_stats have converted into percpu_counter, > > which convert the error margin from (nr_threads * 64) to approximately > > (nr_cpus ^ 2). However, the new percpu allocation in mm_init() causes a > > performance regression on fork/exec/shell. Even after commit 14ef95be6f55 > > ("kernel/fork: group allocation/free of per-cpu counters for mm struct"), > > the performance of fork/exec/shell is still poor compared to previous > > kernel versions. > > > > To mitigate performance regression, we delay the allocation of percpu > > memory for rss_stats. Therefore, we convert mm's rss stats to use > > percpu_counter atomic mode. For single-thread processes, rss_stat is in > > atomic mode, which reduces the memory consumption and performance > > regression caused by using percpu. For multiple-thread processes, > > rss_stat is switched to the percpu mode to reduce the error margin. > > We convert rss_stats from atomic mode to percpu mode only when the > > second thread is created. > > > > After lmbench test, we can get 2% ~ 4% performance improvement > > for lmbench fork_proc/exec_proc/shell_proc and 6.7% performance > > improvement for lmbench page_fault (before batch mode[1]). > > > > The test results are as follows: > > base base+revert base+this patch > > > > fork_proc 416.3ms 400.0ms (3.9%) 398.6ms (4.2%) > > exec_proc 2095.9ms 2061.1ms (1.7%) 2047.7ms (2.3%) > > shell_proc 3028.2ms 2954.7ms (2.4%) 2961.2ms (2.2%) > > page_fault 0.3603ms 0.3358ms (6.8%) 0.3361ms (6.7%) > > > > [1] https://lore.kernel.org/all/20240412064751.119015-1-wangkefeng.wang@huawei.com/ > > > > ChangeLog: > > v2->v1: > > - Convert rss_stats from atomic mode to percpu mode only when > > the second thread is created per Jan Kara. > > - Compared with v1, the performance data may be different due to > > different test machines. > > > > ZhangPeng (2): > > percpu_counter: introduce atomic mode for percpu_counter > > mm: convert mm's rss stats to use atomic mode > > > > include/linux/mm.h | 50 +++++++++++++++++++++++++++++----- > > include/linux/percpu_counter.h | 43 +++++++++++++++++++++++++++-- > > include/trace/events/kmem.h | 4 +-- > > kernel/fork.c | 18 +++++++----- > > lib/percpu_counter.c | 31 +++++++++++++++++++-- > > 5 files changed, 125 insertions(+), 21 deletions(-) > > > -- > Best Regards, > Peng >