From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61AB9233148 for ; Wed, 16 Jul 2025 15:09:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752678592; cv=none; b=iJGA6yxXNJg0pma+coM4UJP7OV8a5VuxS1nJcbWTYVinyugBvgS3ntNL32KD7xpQR5G/eX3m2GGxzC1mU3itX46wXlw7uMRD2gaatMOP0PyIRgOAHL/9SkvAzzP1bD4MAuoqMEUdKZZRrDW/FNZufRUIHEsNWx8KpIPVl6/BxMU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752678592; c=relaxed/simple; bh=64J9ckrYWsYKtc4CtYsoILnHYb8g4vUVJpysmTKfTag=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: MIME-Version:Content-Type; b=Ef9yjfNXrxSJha2n2ke7rms0hKnItBLgR7NKOmRkiTSJHdKzNyFtYYS2NmBOpwWqCmzyBF/PgJOeSmqEtHyVz+MPiQHkTQWSooS5NkolkH4fctARSI8YDgUDp/8hzVTyLfzBCo6MpB6mMQ+DMZLBo0GmG9xwIz8U8/Ptf4vOi6Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KtMNtrOz; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KtMNtrOz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752678589; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=64J9ckrYWsYKtc4CtYsoILnHYb8g4vUVJpysmTKfTag=; b=KtMNtrOzo1THqzGrdgVi3lQD+6tdJwiip8OWabcNnR83xrS8LipmBQ9Nhc3nhsdyc2vpZf jqqB+783CGEzSFf9raqkNNqsCPu1KJREe/dfpXlbPBOt+F/VlzMRJg+ifD3HPCcFO99HtH HZ42rKD4zXSxLS/aheKLtyqfQGyYoJM= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-562-hlKbl0VfNZWRfbbUIfu09w-1; Wed, 16 Jul 2025 11:09:47 -0400 X-MC-Unique: hlKbl0VfNZWRfbbUIfu09w-1 X-Mimecast-MFC-AGG-ID: hlKbl0VfNZWRfbbUIfu09w_1752678587 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-3a50816ccc6so4132363f8f.1 for ; Wed, 16 Jul 2025 08:09:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752678586; x=1753283386; h=mime-version:user-agent:content-transfer-encoding:autocrypt :references:in-reply-to:date:cc:to:from:subject:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=s60Sp6skjO7MztEg1NVdWh+PMYIugCHc0j0VBqr0PaY=; b=PqzbKwhpaufYkpwCUyPWeESr6lGTv4JvVOc8BfA5iw6eHijhzQH/jnSgeiMhbPRi6R TUR1Qt7qQCEzS2tqlQKkdNNUeoeEJlfUR1Gb7xMH3PcOmqrrhLugirVd2t53HlfL49w7 riJozpiLvoc/pMvBbvoeQEcgmYnieYX/Aur+5VGuznB6K+Y8TtR02S6vhsja98lS41qV csUaLLy6mSO5MPukpuPiIU/4e6/vM8hBS+BLqG8obyKYShzGmd/XKkIjnP3UWL0Su7G1 Y96ee96y+eaZ3pKi6PO3bzQShlUsPL9h2l9NFosK28xg17tDa+FsxbESuY7vIXFmZlkh KYjw== X-Forwarded-Encrypted: i=1; AJvYcCXX9m1Kr9a1gsSB36r9qSCTSlTblKJQQeLEz/jcU7RRY9zFShGq2OVJV6y6M+q5q39aHWmG6QDVGeCHxPzUUDw+KHY=@vger.kernel.org X-Gm-Message-State: AOJu0YxvGozs9TT1UkjqwY1sILW30TQMT5+pEsovXPeYw5wPIeqbBlYJ xzE63wM5m7qh1NEENjQWJnX44Ul5C28mKetIAMSTBjmfWWuoEjXOL7mmI3UhNx8qTt1YwmLrpnb opdGbVLyI445txKxwCAOcCdEJ0N1OtvYfUoq+KvSSGMpeP5mw/JKua9swCI/njFAiJ40Ng6rw/A == X-Gm-Gg: ASbGncso9Uq938uYv9QW611DBPpdRWYJcBoCxA/LZHi4JUGfxNtuoXo9iBf1CdSURzv WHkXW3PhyplhxYmi5OPPhm6OLO8zJurZUM5jcwX1l4t4GPpele+9kadS6ScKxxbeua4aN3iF/UX lZVRho1Kmw5rJraselmA2MeTF+33o4vgG8Zxbs/f9NMWpAEQQtcgUeFGpZQZooqFJC255tMcuHw fmHZ+xpscAL1Hr+n+oaju6KItRFFB6eq5+Si3bD5HFMYC1FYA9LOQkG8zSzfkG3cVEVCQWzZiTK 6IbVS7f4kbwW217JEASLm6ndNPfC5k6lGkbbnHCxv3SnNWEXebZe7B9I2Ux9Ujhr8g== X-Received: by 2002:a5d:5f4e:0:b0:3b5:e6c0:1678 with SMTP id ffacd0b85a97d-3b60e52451dmr2476736f8f.45.1752678586310; Wed, 16 Jul 2025 08:09:46 -0700 (PDT) X-Google-Smtp-Source: AGHT+IF8tq87kRXSdlB+5Kbof387zmqH3pRO5qbk4swo5Gnn+EKJzZUxNtFjV0EHj+7pRXCTD5Wz/A== X-Received: by 2002:a5d:5f4e:0:b0:3b5:e6c0:1678 with SMTP id ffacd0b85a97d-3b60e52451dmr2476719f8f.45.1752678585835; Wed, 16 Jul 2025 08:09:45 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([185.107.56.42]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8dc2147sm18242526f8f.32.2025.07.16.08.09.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jul 2025 08:09:45 -0700 (PDT) Message-ID: Subject: Re: [PATCH v3 12/17] sched: Adapt sched tracepoints for RV task model From: Gabriele Monaco To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Steven Rostedt , Masami Hiramatsu , linux-trace-kernel@vger.kernel.org, Nam Cao , Tomas Glozar , Juri Lelli , Clark Williams , John Kacur Date: Wed, 16 Jul 2025 17:09:43 +0200 In-Reply-To: <20250716123832.GW1613200@noisy.programming.kicks-ass.net> References: <20250715071434.22508-1-gmonaco@redhat.com> <20250715071434.22508-13-gmonaco@redhat.com> <20250716123832.GW1613200@noisy.programming.kicks-ass.net> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0ByZWRoYXQuY29tPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmbiuWMCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfJzZgD/TXjnqCyqaZH/Y2w+YVbvm93WX2eqBqiVZ6VEjTuGNs8A/iPrKbzdWC7AicnK xyhmqeUWOzFx5P43S1E1dhsrLWgP User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: hb_qXCvX0T_GAUsaUHHgKrIb7rnuSzfNsjR0aisHQ38_1752678587 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2025-07-16 at 14:38 +0200, Peter Zijlstra wrote: > On Tue, Jul 15, 2025 at 09:14:29AM +0200, Gabriele Monaco wrote: > > Add the following tracepoints: > > * sched_set_need_resched(tsk, cpu, tif) > > =C2=A0=C2=A0=C2=A0 Called when a task is set the need resched [lazy] fl= ag > > * sched_switch_vain(preempt, tsk, tsk_state) > > =C2=A0=C2=A0=C2=A0 Called when a task is selected again during __schedu= le > > =C2=A0=C2=A0=C2=A0 i.e. prev =3D=3D next =3D=3D tsk : no real context s= witch >=20 > > @@ -6592,6 +6598,7 @@ static bool try_to_block_task(struct rq *rq, > > struct task_struct *p, > > =C2=A0=09int flags =3D DEQUEUE_NOCLOCK; > > =C2=A0 > > =C2=A0=09if (signal_pending_state(task_state, p)) { > > +=09=09trace_sched_set_state_tp(p, TASK_RUNNING, true); > > =C2=A0=09=09WRITE_ONCE(p->__state, TASK_RUNNING); > > =C2=A0=09=09*task_state_p =3D TASK_RUNNING; > > =C2=A0=09=09return false; >=20 > I'm confused on the purpose of this. How does this relate to say the > wakeup in signal_wake_up_state() ? Also this adds more context: models like sssw (in this series) expect that, after a task is set to sleepable, it either goes to sleep or is woken up/set to runnable. In this specific case, the task is set to runnable without tracing it, so the model doesn't know what happened, since it may not see a wakeup after that (the task is already runnable). Now I'm not sure if there are other events that we are guaranteed to see to reconstruct this specific case (at some point we should see the signal, I assume). This just simplified things as that is the only state change that was not traced. Am I missing anything obvious here? Thanks, Gabriele