From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB368C433DF for ; Fri, 17 Jul 2020 12:51:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E6D020759 for ; Fri, 17 Jul 2020 12:51:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594990307; bh=U9B3Aohw78O/eD7BbCEY0csjKD1Rg0sjK5ciTtxBuV0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dtq0eOu1cS1PeJJXq7eTddwhJDrGOLRvjPHOkMoVkZhQOkrzE8k9ylYX26cTQq0e/ xZtCfSLCRZ42Dxmdd6s8r3zHLkrXZsTroq1Y7rImP7QY2DE2OoXqcGnl2elV0TXJYi 8WFpwGg3kTg3S++PMRI3O96TdVT5HhSlHh2P6r/U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726696AbgGQMvq (ORCPT ); Fri, 17 Jul 2020 08:51:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:52980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726238AbgGQMvp (ORCPT ); Fri, 17 Jul 2020 08:51:45 -0400 Received: from localhost (lfbn-ncy-1-317-216.w83-196.abo.wanadoo.fr [83.196.152.216]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 416562070A; Fri, 17 Jul 2020 12:51:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594990304; bh=U9B3Aohw78O/eD7BbCEY0csjKD1Rg0sjK5ciTtxBuV0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dPs9F2X0GwNG2NNwcEhdLaAXdIxdu57hofwauDJc5y1FFs8jqNTb+pZDXmp6qFecC tx7EFGgGmtIlZXctAO0Rn0GupZwt1eTSo5TrCybyZYGk08rBX5+GYtfNb3VFqK6Bqq 89Fh9ooK7s8PoijqiyiwzKHsMTyb3auKLMon+qUo= Date: Fri, 17 Jul 2020 14:51:42 +0200 From: Frederic Weisbecker To: Anna-Maria Behnsen Cc: Thomas Gleixner , LKML , Peter Zijlstra , Juri Lelli Subject: Re: [PATCH 4/9] timers: Always keep track of next expiry Message-ID: <20200717125141.GA25465@lenoir> References: <20200707013253.26770-1-frederic@kernel.org> <20200707013253.26770-5-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 14, 2020 at 10:49:28AM +0200, Anna-Maria Behnsen wrote: > Hi Frederic, > > On Tue, 7 Jul 2020, Frederic Weisbecker wrote: > > > So far next expiry was only tracked while the CPU was in nohz_idle mode > > in order to cope with missing ticks that can't increment the base->clk > > periodically anymore. > > > > We are going to expand that logic beyond nohz in order to spare timers > > softirqs so do it unconditionally. > > > > Signed-off-by: Frederic Weisbecker > > Cc: Peter Zijlstra > > Cc: Anna-Maria Gleixner > > Cc: Juri Lelli > > --- > > kernel/time/timer.c | 36 +++++++++++++++++++----------------- > > 1 file changed, 19 insertions(+), 17 deletions(-) > > > > diff --git a/kernel/time/timer.c b/kernel/time/timer.c > > index acf7cb8c09f8..8a4138e47aa4 100644 > > --- a/kernel/time/timer.c > > +++ b/kernel/time/timer.c > > @@ -558,8 +558,22 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) > > * timer is not deferrable. If the other CPU is on the way to idle > > * then it can't set base->is_idle as we hold the base lock: > > */ > > - if (!base->is_idle) > > - return; > > + if (base->is_idle) > > + wake_up_nohz_cpu(base->cpu); > > +} > > + > > +/* > > + * Enqueue the timer into the hash bucket, mark it pending in > > + * the bitmap and store the index in the timer flags. > > + */ > > +static void enqueue_timer(struct timer_base *base, struct timer_list *timer, > > + unsigned int idx) > > +{ > > + hlist_add_head(&timer->entry, base->vectors + idx); > > + __set_bit(idx, base->pending_map); > > + timer_set_idx(timer, idx); > > + > > + trace_timer_start(timer, timer->expires, timer->flags); > > > > /* Check whether this is the new first expiring timer: */ > > if (time_after_eq(timer->expires, base->next_expiry)) > > @@ -578,21 +592,7 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) > > } else { > > base->next_expiry = timer->expires; > > } > > - wake_up_nohz_cpu(base->cpu); > > -} > > > > -/* > > - * Enqueue the timer into the hash bucket, mark it pending in > > - * the bitmap and store the index in the timer flags. > > - */ > > -static void enqueue_timer(struct timer_base *base, struct timer_list *timer, > > - unsigned int idx) > > -{ > > - hlist_add_head(&timer->entry, base->vectors + idx); > > - __set_bit(idx, base->pending_map); > > - timer_set_idx(timer, idx); > > - > > - trace_timer_start(timer, timer->expires, timer->flags); > > trigger_dyntick_cpu(base, timer); > > } > > > > Could you please split those two hunks which do only a restructuring into a > separate patch? The problem is that those hunks are not only a restructuring but they also change the way we update next_expiry, since we do it outside idle context. And that update won't make sense without the proper initialization of next_expiry that comes later in the patch. Thanks.