Message-ID: <4702C897.3030301@linux.intel.com>
Date: Tue, 02 Oct 2007 15:39:19 -0700
From: Arjan van de Ven <arjan@linux.intel.com>
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>,
       Anders Bostr?m <anders@bostrom.dyndns.org>,
       linux-kernel@vger.kernel.org
Subject: Re: PROBLEM: high load average when idle
References: <20071002.233731.119908363.anders@bostrom.dyndns.org> <20071002150748.906970bc.akpm@linux-foundation.org> <alpine.LFD.0.999.0710021514040.3579@woody.linux-foundation.org>
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Linus Torvalds wrote:
> 
> I wonder if the whole "round_jiffies()" thing should be written so that it 
> never rounds down, or at least never rounds down to before the current 
> second!

that's what it is supposed to do already...

166
167         if (j <= jiffies) /* rounding ate our timeout entirely; */
168                 return original;
169         return j;
170 }

so there is always a gap of at least 1 jiffie no matter what


> 
> I have to say, I also think it's a bit iffy to do "round_jiffies()" at all 
> in that per-CPU kind of way. The "per-cpu" thing is quite possibly going 
> to change by the time we actually add the timer, so the goal of trying to 
> get wakeups to happen in "bunches" per CPU should really be done by 
> setting a flag on the timer itself - so that we could do that rounding 
> when the timer is actually added to the per-cpu queues!

it's pretty much the same thing though
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