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Tue, 27 Oct 2026 02:53:05 -0700 (PDT) Received: from scheduler.schedules ([85.100.66.184]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e3ebc3dd7sm21521407f8f.15.2026.10.27.02.53.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 02:53:05 -0700 (PDT) Date: Tue, 27 Oct 2026 12:53:02 +0300 From: Kayra Cizmeci To: K Prateek Nayak Cc: albin_yang@163.com, albinwyang@tencent.com, bsegall@google.com, chen.yu@linux.dev, dietmar.eggemann@arm.com, juri.lelli@redhat.com, linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com, peterz@infradead.org, rostedt@goodmis.org, vincent.guittot@linaro.org, vschneid@redhat.com Subject: Re: [PATCH] sched/stats: Fix run_delay over-count for proxy-migrated blocked donors Message-ID: References: <72a6eb77-0461-477b-a0e9-c06a486e3e0e@amd.com> <20261026133831.4111227-1-albin_yang@163.com> <36f12b2f-9fc8-46e9-8312-536c918722f1@amd.com> <4ac4564e-08fb-4639-a89e-a2ad54cee3f7@amd.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Tue, Oct 27, 2026 at 03:15:40PM +0530, K Prateek Nayak wrote: > On 10/27/2026 12:22 PM, Kayra Cizmeci wrote: > > I think this fixes the issue. BTW I think this should skip curr, no? > > On a case like this: > > > > C holds M1 in CPU0, D waits that mutex in CPU1. A holds mutex M2 in > > CPU2. B is the working task on CPU1 but it wants mutex M2 and we enter > > __schedule(). B gets is_blocked. D gets chosen. We open the rq lock to > > get D to CPU0. While this happens A drops the mutex and wakes up B. > > we enter ttwu_runnable() and B is still curr. And we start the timer. > > Good catch that! > > > Or am I MISSSING something? > > I can't believe something like wait time accounting can get this > complicated! Anyhow, We can perhaps call sched_info_enqueue() in TBH, me neither :-). > ttwu_runnable() instead of proxy_needs_return() like: I was thinking about that too! LGTM. FWIW, this depends on is_blocked check in sched_info_enqueue(). Wei, what do you think? Will this work for you? > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 04b62c16fa8c..d5758b78b741 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3956,6 +3956,8 @@ static int ttwu_runnable(struct task_struct *p, int wake_flags) > * it should preempt the task that is current now. > */ > wakeup_preempt(rq, p, wake_flags | WF_TTWU_RQ); > + /* Start accounting wait time. */ > + sched_info_enqueue(rq, p); > } > ttwu_do_wakeup(p); > return 1; > --- > > -- > Thanks and Regards, > Prateek > Thanks! Kayra