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b=0C38FejyFWntdFzurye3Ptv78WQkibel8t059iY353tBNabNrhDptyQ80YkxDqQDG Mq8lv+iEW00ZWlBg9911g3qDE64P7mVWyihvClRXZl6aS9wkrXgVx372F99Ixxpn0H ispIKjuxzfy0Ko6MyZPXPMa1nyxVhFfFN3Q7I91w= Date: Tue, 3 Dec 2024 17:08:16 -0800 From: Andrew Morton To: Cc: , , , , , , , , , , , , , , Subject: Re: [PATCH linux next] delayacct: add delay max to record delay peak Message-Id: <20241203170816.3fe81941fe1866ca1672eba8@linux-foundation.org> In-Reply-To: <20241203164848805CS62CQPQWG9GLdQj2_BxS@zte.com.cn> References: <20241203164848805CS62CQPQWG9GLdQj2_BxS@zte.com.cn> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 9arubitozwrr1fiwewfkotrocm7xpsfz X-Rspamd-Queue-Id: 3C16FA0013 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1733274489-551806 X-HE-Meta: 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 y9tHH1kY H4o0Pmvrsp5fDjoyK99bNhEXExR91uIgSJ+PEN2GMziuTVV3d4xegKM5jXXrKgCYs2wH4oDJdwAMMi8iJ1HhPPc3jiz/LEWiHOuEKnZgbcSbqS0jGFms0x+zTcv+q62DQbfaIHbjOCC9uQuHywVKwPY9d/S2dpQemuJS6fLgzLjQB/APNz40JB4ScTXjjmGdl87lnETvHe6uX4Z/hiwbRnk1WHP5xwflFvBgA601damQkDWDNxlxENwrrSH6W7L8Y0HpEkcooyi7jqwL2ah5t/iiTUggO4VctRq7ptXmPyh/xk1pbpVVXt/I68A== 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 Tue, 3 Dec 2024 16:48:48 +0800 (CST) wrote: > From: Wang Yaxin > > Introduce the use cases of delay max, which can help quickly detect > potential abnormal delays in the system and record the types and > specific details of delay spikes. > > Problem > ======== > Delay accounting can track the average delay of processes to show > system workload. However, when a process experiences a significant > delay, maybe a delay spike, which adversely affects performance, > getdelays can only display the average system delay over a period > of time. Yet, average delay is unhelpful for diagnosing delay peak. > It is not even possible to determine which type of delay has spiked, > as this information might be masked by the average delay. > > Solution > ========= > the 'delay max' can display delay peak since the system's startup, > which can record potential abnormal delays over time, including > the type of delay and the maximum delay. This is helpful for > quickly identifying crash caused by delay. Seems sensible, and the implementation is straightforward. I'll queue it for testing and review. > include/linux/delayacct.h | 7 ++++ > include/linux/sched.h | 3 ++ > include/uapi/linux/taskstats.h | 9 ++++++ > kernel/delayacct.c | 35 ++++++++++++++------ > kernel/sched/stats.h | 5 ++- > tools/accounting/getdelays.c | 59 ++++++++++++++++++++-------------- Please prepare a v2 which includes an update to Documentation/accounting/delay-accounting.rst. > > ... > > --- a/kernel/delayacct.c > +++ b/kernel/delayacct.c > @@ -95,7 +95,7 @@ void __delayacct_tsk_init(struct task_struct *tsk) > * Finish delay accounting for a statistic using its timestamps (@start), > * accumalator (@total) and @count And I wouldn't be offended if v2 fixed that spelling error! "accumulator".