linux-kernel - Re: [RFC] time: xtime

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Message-ID: <1304701778.3066.165.camel@edumazet-laptop>
Date:	Fri, 06 May 2011 19:09:38 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	john stultz <johnstul@...ibm.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Anton Blanchard <anton@...ba.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC] time: xtime_lock is held too long

Le vendredi 06 mai 2011 à 18:59 +0200, Andi Kleen a écrit :
> On Fri, May 06, 2011 at 12:18:27PM +0200, Thomas Gleixner wrote:

> If that code path shows up in profiling. Only the timer interrupt
> did so far.
> 
> > That's the completely wrong aproach, really. If stuff takes too long,
> > then we need to tackle it at the root of the problem and not solve it
> > by sprinkling magic prefetches all over the place.
> 
> If you have a better way to make it faster please share it.
> 

Unless I am very mistaken, it cannot explain my original report of up to
24.000 instructions waiting in ktime_get()

BTW, how many consecutive prefetch() a cpu can 'store/execute' before
throwing away hints ?



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