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From: Takashi Iwai <tiwai@suse.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	alsa-devel@alsa-project.org, Takashi Iwai <tiwai@suse.com>,
	Jaroslav Kysela <perex@perex.cz>
Subject: Re: [patch 04/11] ALSA: pcsp: Make hrtimer forwarding more robust
Date: Tue, 28 Sep 2021 10:58:28 +0200	[thread overview]
Message-ID: <s5ho88dnkjv.wl-tiwai@suse.de> (raw)
In-Reply-To: <20210923153339.623208460@linutronix.de>

On Thu, 23 Sep 2021 18:04:25 +0200,
Thomas Gleixner wrote:
> 
> The hrtimer callback pcsp_do_timer() prepares rearming of the timer with
> hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to
> forward the expiry time of the hrtimer by a multiple of the period argument
> so that the expiry time greater than the time provided in the 'now'
> argument.
> 
> pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry
> time as 'now' argument. That's providing a periodic timer expiry, but is
> not really robust when the timer callback is delayed so that the resulting
> new expiry time is already in the past which causes the callback to be
> invoked immediately again. If the timer is delayed then the back to back
> invocation is not really making it better than skipping the missed
> periods. Sound is distorted in any case.
> 
> Use hrtimer_forward_now() which ensures that the next expiry is in the
> future. This prevents hogging the CPU in the timer expiry code and allows
> later on to remove hrtimer_forward() from the public interfaces.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: alsa-devel@alsa-project.org
> Cc: Takashi Iwai <tiwai@suse.com>
> Cc: Jaroslav Kysela <perex@perex.cz>

Thanks, applied now to sound git tree.


Takashi

WARNING: multiple messages have this Message-ID (diff)
From: Takashi Iwai <tiwai@suse.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
	alsa-devel@alsa-project.org, LKML <linux-kernel@vger.kernel.org>,
	Takashi Iwai <tiwai@suse.com>
Subject: Re: [patch 04/11] ALSA: pcsp: Make hrtimer forwarding more robust
Date: Tue, 28 Sep 2021 10:58:28 +0200	[thread overview]
Message-ID: <s5ho88dnkjv.wl-tiwai@suse.de> (raw)
In-Reply-To: <20210923153339.623208460@linutronix.de>

On Thu, 23 Sep 2021 18:04:25 +0200,
Thomas Gleixner wrote:
> 
> The hrtimer callback pcsp_do_timer() prepares rearming of the timer with
> hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to
> forward the expiry time of the hrtimer by a multiple of the period argument
> so that the expiry time greater than the time provided in the 'now'
> argument.
> 
> pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry
> time as 'now' argument. That's providing a periodic timer expiry, but is
> not really robust when the timer callback is delayed so that the resulting
> new expiry time is already in the past which causes the callback to be
> invoked immediately again. If the timer is delayed then the back to back
> invocation is not really making it better than skipping the missed
> periods. Sound is distorted in any case.
> 
> Use hrtimer_forward_now() which ensures that the next expiry is in the
> future. This prevents hogging the CPU in the timer expiry code and allows
> later on to remove hrtimer_forward() from the public interfaces.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: alsa-devel@alsa-project.org
> Cc: Takashi Iwai <tiwai@suse.com>
> Cc: Jaroslav Kysela <perex@perex.cz>

Thanks, applied now to sound git tree.


Takashi

  reply	other threads:[~2021-09-28  8:58 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-23 16:04 [patch 00/11] hrtimers: Cleanup hrtimer_forward() [ab]use Thomas Gleixner
2021-09-23 16:04 ` [Intel-gfx] " Thomas Gleixner
2021-09-23 16:04 ` Thomas Gleixner
2021-09-23 16:04 ` [patch 01/11] hrtimer: Add a mechanism to catch runaway timers Thomas Gleixner
2021-09-24  8:16   ` Dmitry Vyukov
2021-09-23 16:04 ` [patch 02/11] mac80211-hwsim: Fix late beacon hrtimer handling Thomas Gleixner
2021-09-23 16:04 ` [patch 03/11] net: iosm: Use hrtimer_forward_now() Thomas Gleixner
2021-09-23 16:04 ` [patch 04/11] ALSA: pcsp: Make hrtimer forwarding more robust Thomas Gleixner
2021-09-23 16:04   ` Thomas Gleixner
2021-09-28  8:58   ` Takashi Iwai [this message]
2021-09-28  8:58     ` Takashi Iwai
2021-09-23 16:04 ` [patch 05/11] can: bcm: Use hrtimer_forward_now() Thomas Gleixner
2021-10-13 13:59   ` Marc Kleine-Budde
2021-09-23 16:04 ` [patch 06/11] power: reset: ltc2952: " Thomas Gleixner
2021-09-27 12:34   ` Sebastian Reichel
2021-09-23 16:04 ` [patch 07/11] drm/i915/pmu: " Thomas Gleixner
2021-09-23 16:04   ` [Intel-gfx] " Thomas Gleixner
2021-09-24  9:03   ` Tvrtko Ursulin
2021-09-23 16:04 ` [patch 08/11] signal: Move itimer rearming into itimer code Thomas Gleixner
2021-09-23 16:04 ` [patch 09/11] posix-timers: Fixup stale commnt and reduce ifdeffery Thomas Gleixner
2021-09-23 16:04 ` [patch 10/11] posix-timers: Use hrtimer_forward_now() Thomas Gleixner
2021-09-23 16:04 ` [patch 11/11] hrtimer: Make hrtimer_forward() private to core timer code Thomas Gleixner

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