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Message-ID: <20110506165359.GE11636@one.firstfloor.org> Date: Fri, 6 May 2011 18:53:59 +0200 From: Andi Kleen <andi@...stfloor.org> To: Ingo Molnar <mingo@...e.hu> Cc: Thomas Gleixner <tglx@...utronix.de>, Andi Kleen <andi@...stfloor.org>, Eric Dumazet <eric.dumazet@...il.com>, 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> Subject: Re: [RFC] time: xtime_lock is held too long > Then precise measurements have to be done on the source of cache misses, the > total cost of the timer interrupt, etc. What we did was profiling the remote node cache misses using raw offcore events, and the xtime code was high up. I cannot share exact numbers for various reasons, but it was an improvement on a hard to improve workload. > I.e. this should be analyzed and improved properly, not just sloppily slapping > a few prefetches here and there, which wont really *solve* anything ... Well it made things faster. That's definitely something. I agree the cache lines need to be consolidated in a proper way. But well placed prefetches by themselves can be a useful tool, and placing them based on stable profile results is not "sloppy". -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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