linux-kernel - Re: [PATCH 2/3] timer: Check thread timers only when there are active thread timers

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Message-ID: <1440610876.23728.101.camel@j-VirtualBox>
Date:	Wed, 26 Aug 2015 10:41:16 -0700
From:	Jason Low <jason.low2@...com>
To:	George Spelvin <linux@...izon.com>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	jason.low2@...com
Subject: Re: [PATCH 2/3] timer: Check thread timers only when there are
 active thread timers

On Wed, 2015-08-26 at 13:04 -0400, George Spelvin wrote:
> -	check_thread_timers(tsk, &firing);
> +	if (!task_cputime_zero(&tsk->cputime_expires))
> +		check_thread_timers(tsk, &firing);
> 
> Sincere question; I'm not certain myself: would it make more sense to put
> this shortcut into check_thread_timers()?
> 
> It seems more like an optimization of that function than something the
> caller needs to know about.

Yes, I also thought it might be better if we add something like:

	if (task_cputime_zero(&tsk->cputime_expires)
		return;

in check_thread_timers(). The reason I made it this way though is
because in the next few lines, we do a similar check before calling
check_process_timers(), and I wanted to keep things consistent.

However, perhaps we can consider also moving that
tsk->signal->cputimer.running check into check_process_timers() too.

Thanks for the suggestions.

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