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[36.236.186.165]) by smtp.gmail.com with ESMTPSA id x13-20020a17090a294d00b001e0cc5b13c6sm17170183pjf.26.2022.06.08.16.12.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jun 2022 16:12:10 -0700 (PDT) Date: Thu, 9 Jun 2022 07:12:05 +0800 From: Steven Lung <1030steven@gmail.com> To: Vincent Guittot Cc: Randy Dunlap , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/pelt: Fix bracket typo Message-ID: References: <20220608150008.57629-1-1030steven@gmail.com> <3193fcc9-c672-19d9-a2e2-ad67809dd20b@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 08, 2022 at 10:14:06PM +0200, Vincent Guittot wrote: > On Wed, 8 Jun 2022 at 18:30, 龍帆軒 <1030steven@gmail.com> wrote: > > > > > > Randy Dunlap 於 2022年6月8日 下午11:33 寫道： > > > > > > > > On 6/8/22 08:00, Steven Lung wrote: > > > > The second bracket describing the range is inverted, this patch > > will fix it. > > > > Signed-off-by: Steven Lung <1030steven@gmail.com> > > --- > > kernel/sched/pelt.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c > > index 0f3107682..ed82cfba9 100644 > > --- a/kernel/sched/pelt.c > > +++ b/kernel/sched/pelt.c > > @@ -233,7 +233,7 @@ ___update_load_sum(u64 now, struct sched_avg *sa, > > * When syncing *_avg with *_sum, we must take into account the current > > * position in the PELT segment otherwise the remaining part of the segment > > * will be considered as idle time whereas it's not yet elapsed and this will > > - * generate unwanted oscillation in the range [1002..1024[. > > > > > > Is the above the same as range [1002..1024). > > ? I.e. 1002-1023 inclusive (or 1024 excluded)? > > yes, 1024 was excluded from the range because we reached 1024 when > period_contrib == 1024 but when period_contrib == 1024 we decayed and > period_contrib becomes 0 and the load_avg went down to 1002. > > Before the changes, the load_avg for default weight was > 1024*(LOAD_AVG_MAX-1024+period_contrib)/LOAD_AVG_MAX > if period_contrib == 0 ie the beg of the window we've got a load_avg of 1002 > if period_contrib == 1023 ie the end of the window we've got a load of > int(1023.97)==1023 > > In French, we use [1002..1024[ but english version is [1002..1024) Seems this patch should not be applied, thank Vincent for the explanation. > > > > > + * generate unwanted oscillation in the range [1002..1024]. > > * > > * The max value of *_sum varies with the position in the time segment and is > > * equals to : > > > > > > -- > > ~Randy > > > > > > In the patch that the author submitted[1] for this comment, he mentioned that the value 1024 can be obtained. > > So I think we should use brackets instead of parenthesis. > > > > [1]: https://lore.kernel.org/all/20200506155301.14288-1-vincent.guittot@linaro.org/T/#u > > > > -- > > Steven > >