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Tue, 15 Apr 2025 04:30:13 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGJg1T2zGt/c3xlxN6DHLM3imOYewefdPkz7tHiuJsnsyUasuwt1RmXBHXcd/5pyXlDyPwUVg== X-Received: by 2002:a05:6402:5106:b0:5ed:5e44:90cd with SMTP id 4fb4d7f45d1cf-5f37011737bmr13348111a12.32.1744716613342; Tue, 15 Apr 2025 04:30:13 -0700 (PDT) Received: from [127.0.0.1] ([195.174.134.30]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5f36f06b244sm6657134a12.45.2025.04.15.04.30.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Apr 2025 04:30:12 -0700 (PDT) Date: Tue, 15 Apr 2025 11:30:07 +0000 (UTC) From: Gabriele Monaco To: Nam Cao Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Tomas Glozar , Juri Lelli Message-ID: <4e4b9c63-1b86-4d96-bcf3-0cdee8ba7c9e@redhat.com> In-Reply-To: <20250415110455.0Qj-4EN2@linutronix.de> References: <20250404084512.98552-11-gmonaco@redhat.com> <20250404084512.98552-17-gmonaco@redhat.com> <20250413150540.3ZW7XJVs@linutronix.de> <20250415110455.0Qj-4EN2@linutronix.de> Subject: Re: [RFC PATCH 6/9] sched: Treat try_to_block_task with pending signal as wakeup Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Correlation-ID: <4e4b9c63-1b86-4d96-bcf3-0cdee8ba7c9e@redhat.com> 2025-04-15T11:05:06Z Nam Cao : > On Mon, Apr 14, 2025 at 12:31:12PM +0200, Gabriele Monaco wrote: >> Mmh, that's a good point. >> The thing is: this happens when the signal is generated while we are >> scheduling (on different CPUs), so we take a short-cut and put the task >> to running directly. >> This thing is already racy, so we may or may not see the waking/wakeup. >> >> Now probably waking shouldn't be there for the reason you said, but I'm >> not sure a wakeup not following a waking would be correct either. >> I might be missing something here, though. > > I'm not familiar with signal and sched, so I don't have anything more to > add, sorry. > No worries, that was helpful already! > I presume this is to make the srs monitor works? Perhaps it is possible to > modify the model so that this patch is not required? Let me stare at srs, > maybe I will have something.. Yeah, that's another option, we could have a special case just for that, but I wanted to avoid it. But still, let me know if you got a good idea how to rearrange it! Thanks, Gabriele