From: Peter Zijlstra <peterz@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH 2/2] block: Convert BDI proportion calculations to flexible proportions
Date: Fri, 18 May 2012 16:34:37 +0200 [thread overview]
Message-ID: <1337351677.573.44.camel@twins> (raw)
In-Reply-To: <20120518142443.GA6875@quack.suse.cz>
On Fri, 2012-05-18 at 16:24 +0200, Jan Kara wrote:
> Yeah, that should be easy enough so I'll try it that way since I presume
> it's nicer to power usage to use deferred timers if it's reasonably
> possible.
Btw, your current scheme also drifts. Since you do jiffes + 3*HZ you
period might actually be longer if the timer got delayed.
If you keep an external jiffies count like:
unsigned long period_jiffies = jiffies;
void my_timer_func()
{
unsigned long delta = jiffies - period_jiffies;
unsigned long periods = delta / 3*HZ;
age(periods);
period_jiffies += 3*HZ * periods;
mod_timer(&my_timer, period_jiffies);
}
it all works without drift (+- bugs of course).
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next prev parent reply other threads:[~2012-05-18 14:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-15 15:43 [PATCH 0/2 v3] Flexible proportions Jan Kara
2012-05-15 15:43 ` [PATCH 1/2] lib: Proportions with flexible period Jan Kara
2012-05-17 21:35 ` Peter Zijlstra
2012-05-18 14:33 ` Jan Kara
2012-05-17 21:56 ` Peter Zijlstra
2012-05-18 14:42 ` Jan Kara
2012-05-18 10:43 ` Peter Zijlstra
2012-05-18 14:45 ` Jan Kara
2012-05-15 15:43 ` [PATCH 2/2] block: Convert BDI proportion calculations to flexible proportions Jan Kara
2012-05-17 22:04 ` Peter Zijlstra
2012-05-18 14:24 ` Jan Kara
2012-05-18 14:34 ` Peter Zijlstra [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-05-24 16:59 [PATCH 0/2 v4] Flexible proportions Jan Kara
2012-05-24 16:59 ` [PATCH 2/2] block: Convert BDI proportion calculations to flexible proportions Jan Kara
2012-05-28 15:49 ` Sasha Levin
2012-05-29 12:34 ` Jan Kara
2012-05-29 12:38 ` Peter Zijlstra
2012-05-29 12:54 ` Jan Kara
2012-05-31 22:11 ` Jan Kara
2012-05-31 22:26 ` Peter Zijlstra
2012-05-31 22:42 ` Jan Kara
2012-06-01 3:10 ` Fengguang Wu
2012-06-01 10:13 ` Peter Zijlstra
2012-05-03 22:39 [PATCH 0/2 v2] Flexible proportions for BDIs Jan Kara
2012-05-03 22:39 ` [PATCH 2/2] block: Convert BDI proportion calculations to flexible proportions Jan Kara
2012-05-07 14:47 ` Fengguang Wu
2012-05-07 15:21 ` Peter Zijlstra
2012-05-09 11:38 ` Jan Kara
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