From nobody Wed Feb 11 05:14:02 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA060C77B73 for ; Tue, 6 Jun 2023 15:12:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238509AbjFFPMv (ORCPT ); Tue, 6 Jun 2023 11:12:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238391AbjFFPMq (ORCPT ); Tue, 6 Jun 2023 11:12:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4776EE40; Tue, 6 Jun 2023 08:12:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id CDCF9629C8; Tue, 6 Jun 2023 15:12:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E38DC4339B; Tue, 6 Jun 2023 15:12:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686064364; bh=TUuQCM3jhirEhMqYofGh/R4e0sG21Hal+fI5biqfXTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uJJRuHpvRKBZaGY1ZkGv4N2KFZAchtA2sM4jT01xcS7mPrI5y0sXKZkLB4ACtqLQ/ asvk9jxSTJhN69F4LxkrmmzxF+4QaUXZmmeaSmIBT5ahi02mIWxVqHNpiDqUH30Te4 reoHmnOc4riJd0lEQa9+vmZ5lddeXBXVgQiCoYl85mr1It2s6h8k2GTjrNjQeqybbp Ilqan/az9p3aM4S8LV2+ZLVe2mKWc1VXnwIL0FuAKFkeFCGcUtqa59ug4uqs4/K9/W 2DSzKNZfejUtyOc2mjMaPya/XVXEBRkH0C55R0shaAeOeh6JNia/vm/0Fx9SofYHAe SVcJrGAliFiKw== From: Daniel Bristot de Oliveira To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Steven Rostedt Cc: Juri Lelli , William White , Daniel Bristot de Oliveira , Masami Hiramatsu , Jonathan Corbet Subject: [PATCH V3 2/3] tracing/osnoise: Skip running osnoise if all instances are off Date: Tue, 6 Jun 2023 17:12:26 +0200 Message-Id: X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In the case of all tracing instances being off, sleep for the entire period. Q: Why not kill all threads so? A: It is valid and useful to start the threads with tracing off. For example, rtla disables tracing, starts the tracer, applies the scheduling setup to the threads, e.g., sched priority and cgroup, and then begin tracing with all set. Skipping the period helps to speed up rtla setup and save the trace after a stop tracing. Cc: Steven Rostedt Cc: Daniel Bristot de Oliveira Cc: Masami Hiramatsu Cc: Jonathan Corbet Signed-off-by: Daniel Bristot de Oliveira --- kernel/trace/trace_osnoise.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index c265ec5f1726..220172cb874d 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1285,6 +1285,22 @@ static __always_inline void osnoise_stop_tracing(voi= d) rcu_read_unlock(); } =20 +/* + * osnoise_has_tracing_on - Check if there is at least one instance on + */ +static __always_inline int osnoise_has_tracing_on(void) +{ + struct osnoise_instance *inst; + int trace_is_on =3D 0; + + rcu_read_lock(); + list_for_each_entry_rcu(inst, &osnoise_instances, list) + trace_is_on +=3D tracer_tracing_is_on(inst->tr); + rcu_read_unlock(); + + return trace_is_on; +} + /* * notify_new_max_latency - Notify a new max latency via fsnotify interfac= e. */ @@ -1517,13 +1533,16 @@ static struct cpumask save_cpumask; /* * osnoise_sleep - sleep until the next period */ -static void osnoise_sleep(void) +static void osnoise_sleep(bool skip_period) { u64 interval; ktime_t wake_time; =20 mutex_lock(&interface_lock); - interval =3D osnoise_data.sample_period - osnoise_data.sample_runtime; + if (skip_period) + interval =3D osnoise_data.sample_period; + else + interval =3D osnoise_data.sample_period - osnoise_data.sample_runtime; mutex_unlock(&interface_lock); =20 /* @@ -1604,8 +1623,14 @@ static int osnoise_main(void *data) if (osnoise_migration_pending()) break; =20 + /* skip a period if tracing is off on all instances */ + if (!osnoise_has_tracing_on()) { + osnoise_sleep(true); + continue; + } + run_osnoise(); - osnoise_sleep(); + osnoise_sleep(false); } =20 migrate_enable(); --=20 2.38.1