From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 10600664CE for ; Tue, 20 Feb 2024 11:41:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708429320; cv=none; b=GWj6TT8bLPU6YJwYb/41XBFknClv75F7o1dy0BBqUdlvtJqbWI9AFfdwV7jE+shpIETG76JjXxX2+TD/gzen/6hoRI989kf09pWaWcmJ9EHOiVa+QG2bZlz92PfDupaW09DqP1a8yLmTtHzx/FHZYkBAOM+mTmFxIe5kUkkB3gg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708429320; c=relaxed/simple; bh=q++Ve8879Npx2wq1JnlALpXBfW43mRaompH7G7hkYn8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OHxjho22YJHqKGujL5omH3bnmF80vV2c/JaDXNYanp1PKPHu3pW6jdW+9/i6+az+z6KT6OgdauIXrqtgfnoasrPghQa1uZfJhcRZLPx0hgbBs0IgehiCUOlKgxrZ7829GgLIq6dABBJt+rabrzU+arCqGI+2K68NGWX5qwvUpMo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rUjWxzsx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rUjWxzsx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 008D9C433A6; Tue, 20 Feb 2024 11:41:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708429319; bh=q++Ve8879Npx2wq1JnlALpXBfW43mRaompH7G7hkYn8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rUjWxzsxc7b/+LXSnMFEghOioBejkwFTOwX/XcP7a5GLe8qmThsFBC9ENzl2O6M0X pGUvvtRmB+dW1/bamR9c/NQ9mjzbiwxvmDg4joH9rvwYWwhiY1Cax8/XM/cTp3GTyR /NPEm8gFGBigZzbrFCe0PIOf31RI9w+DfHo6Q4yc1oSQxHABGuwYU+gyDUaZwxJGW0 f1RaWdUzl5HQKjtRFFWUlLh9GGdE4yPzByvHzWvu7WifbmtdDQR6jAVm5VMCQ0/FIn lXICU3JuTh4AFEMfgJWJwVtzrC2PipoF3ITA0AMRNEaEK9WnpIPx8ApeMftjsKW2w+ QCrqqsPtKeniw== Date: Tue, 20 Feb 2024 12:41:56 +0100 From: Frederic Weisbecker To: Anna-Maria Behnsen Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , John Stultz , Thomas Gleixner , Eric Dumazet , "Rafael J . Wysocki" , Arjan van de Ven , "Paul E . McKenney" , Rik van Riel , Steven Rostedt , Sebastian Siewior , Giovanni Gherdovich , Lukasz Luba , "Gautham R . Shenoy" , Srinivas Pandruvada , K Prateek Nayak Subject: Re: [PATCH v10a] timers: Move marking timer bases idle into tick_nohz_stop_tick() Message-ID: References: <20240115143743.27827-4-anna-maria@linutronix.de> <20240219085236.10624-1-anna-maria@linutronix.de> <878r3f5s3w.fsf@somnus> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <878r3f5s3w.fsf@somnus> Le Tue, Feb 20, 2024 at 11:48:19AM +0100, Anna-Maria Behnsen a écrit : > Frederic Weisbecker writes: > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 01fb50c1b17e..b93f0e6f273f 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -895,21 +895,6 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) > /* Make sure we won't be trying to stop it twice in a row. */ > ts->timer_expires_base = 0; > > - /* > - * If this CPU is the one which updates jiffies, then give up > - * the assignment and let it be taken by the CPU which runs > - * the tick timer next, which might be this CPU as well. If we > - * don't drop this here, the jiffies might be stale and > - * do_timer() never gets invoked. Keep track of the fact that it > - * was the one which had the do_timer() duty last. > - */ > - if (cpu == tick_do_timer_cpu) { > - tick_do_timer_cpu = TICK_DO_TIMER_NONE; > - ts->do_timer_last = 1; > - } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { > - ts->do_timer_last = 0; > - } > - > /* Skip reprogram of event if it's not changed */ > if (ts->tick_stopped && (expires == ts->next_tick)) { > /* Sanity check: make sure clockevent is actually programmed */ That should work but then you lose the optimization that resets ts->do_timer_last even if the next timer hasn't changed. Thanks. > @@ -938,6 +923,21 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) > trace_tick_stop(1, TICK_DEP_MASK_NONE); > } > > + /* > + * If this CPU is the one which updates jiffies, then give up > + * the assignment and let it be taken by the CPU which runs > + * the tick timer next, which might be this CPU as well. If we > + * don't drop this here, the jiffies might be stale and > + * do_timer() never gets invoked. Keep track of the fact that it > + * was the one which had the do_timer() duty last. > + */ > + if (cpu == tick_do_timer_cpu) { > + tick_do_timer_cpu = TICK_DO_TIMER_NONE; > + ts->do_timer_last = 1; > + } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { > + ts->do_timer_last = 0; > + } > + > ts->next_tick = expires; > > /*