From nobody Fri Dec 19 12:15:23 2025 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 665D02773F3 for ; Fri, 10 Oct 2025 08:34:57 +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=1760085299; cv=none; b=DuSEpLBUC8s5yGTuDRUY7S/ZgpbqTok1CaEjQJ1tBtd+HOlHX8dbgeLSKdY6Kthz5pu1Lt5IPa6VFxEvwbVrQmMmf+SmEnImWajiYvNcypYpUod44+tgg70/nSrTe0ogx1cZKqoZ2IvbIjbciYOh3s+EZJ2zI8WcWUm2NzOFQMg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760085299; c=relaxed/simple; bh=ETcUFRp7Y640qwjOoQZKCzn4RuBAqnHbLA1tNYHmtGY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pa33fH9t4hPgUMTG7SI0hqkjm5kPTb4vF1jfdjojV82cRhec1JLXu8iZvj5k4wiX/Kbon+qBDFHvJ6emuBcciOeNhNzDFE9NUQbwx+CHVCbou1EqPyRgiS6hC01ZgZlr4UTlj3w6SPjc2QUfCajeLVEUavOng9mN1N5QTitM06A= 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=MkQ/7G7r; 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="MkQ/7G7r" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760085296; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=41+4ai0rqazcMx3eP0C0LY+GmTK8OcTNHQBt4S97B2Q=; b=MkQ/7G7rbFWGYyNYavV8KEeNvqrLE38uDYlPqh2vl+piddAf0omdz1m4tTeuTp6yORTMMa SBOD6MnBACPaCzN7rkGyoN3C2TQbHr/4lc8C6mjs+1PHF5ol4ejeTvIDPcCNwjSZVSWdu3 AKePDmEVGACo+eOL6E2OaQ3quRZo324= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-520-kjH4I658MX6CxCuls_x2PQ-1; Fri, 10 Oct 2025 04:34:53 -0400 X-MC-Unique: kjH4I658MX6CxCuls_x2PQ-1 X-Mimecast-MFC-AGG-ID: kjH4I658MX6CxCuls_x2PQ_1760085292 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DF413195608C; Fri, 10 Oct 2025 08:34:51 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.44.32.197]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7CAFA1955F42; Fri, 10 Oct 2025 08:34:47 +0000 (UTC) From: Tomas Glozar To: Steven Rostedt , Masami Hiramatsu , Jonathan Corbet Cc: linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Mathieu Desnoyers , John Kacur , Luis Goncalves , Costa Shulyupin , Crystal Wood , Attila Fazekas , Tomas Glozar Subject: [PATCH 8/9] Documentation/trace: Specify exact priority for timerlat Date: Fri, 10 Oct 2025 10:33:37 +0200 Message-ID: <20251010083338.478961-9-tglozar@redhat.com> In-Reply-To: <20251010083338.478961-1-tglozar@redhat.com> References: <20251010083338.478961-1-tglozar@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" The timerlat tracer documentation mentions that threads are created with real-time priority, but does not mention which priority and scheduling class is used. Add the information so that users do not have to look it up in trace_osnoise.c. Signed-off-by: Tomas Glozar --- Documentation/trace/timerlat-tracer.rst | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/Documentation/trace/timerlat-tracer.rst b/Documentation/trace/= timerlat-tracer.rst index 53a56823e903..68d429d454a5 100644 --- a/Documentation/trace/timerlat-tracer.rst +++ b/Documentation/trace/timerlat-tracer.rst @@ -43,12 +43,12 @@ It is possible to follow the trace by reading the trace= file:: <...>-868 [001] .... 54.030347: #2 context thread ti= mer_latency 4351 ns =20 =20 -The tracer creates a per-cpu kernel thread with real-time priority that -prints two lines at every activation. The first is the *timer latency* -observed at the *hardirq* context before the activation of the thread. -The second is the *timer latency* observed by the thread. The ACTIVATION -ID field serves to relate the *irq* execution to its respective *thread* -execution. +The tracer creates a per-cpu kernel thread with real-time priority +SCHED_FIFO:95 that prints two lines at every activation. The first is +the *timer latency* observed at the *hardirq* context before the activation +of the thread. The second is the *timer latency* observed by the thread. +The ACTIVATION ID field serves to relate the *irq* execution to its +respective *thread* execution. =20 The *irq*/*thread* splitting is important to clarify in which context the unexpected high value is coming from. The *irq* context can be --=20 2.51.0