From: Andi Kleen <andi@firstfloor.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Andi Kleen <andi@firstfloor.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
john stultz <johnstul@us.ibm.com>,
lkml <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Anton Blanchard <anton@samba.org>
Subject: Re: [RFC] time: xtime_lock is held too long
Date: Fri, 6 May 2011 18:53:59 +0200 [thread overview]
Message-ID: <20110506165359.GE11636@one.firstfloor.org> (raw)
In-Reply-To: <20110506102232.GA11036@elte.hu>
> 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
next prev parent reply other threads:[~2011-05-06 16:54 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-04 3:11 [PATCH] time: Add locking to xtime access in get_seconds() John Stultz
2011-05-04 3:52 ` Andi Kleen
2011-05-05 2:54 ` john stultz
2011-05-05 5:44 ` Eric Dumazet
2011-05-05 6:21 ` john stultz
2011-05-05 6:50 ` Eric Dumazet
2011-05-05 8:14 ` Paul E. McKenney
2011-05-05 18:51 ` john stultz
2011-05-05 14:04 ` [RFC] time: xtime_lock is held too long Eric Dumazet
2011-05-05 14:39 ` Thomas Gleixner
2011-05-05 15:08 ` Eric Dumazet
2011-05-05 15:59 ` Thomas Gleixner
2011-05-05 21:01 ` Andi Kleen
2011-05-06 1:41 ` Eric Dumazet
2011-05-06 6:55 ` Andi Kleen
2011-05-06 10:18 ` Thomas Gleixner
2011-05-06 10:22 ` Ingo Molnar
2011-05-06 16:53 ` Andi Kleen [this message]
2011-05-07 8:20 ` Ingo Molnar
2011-05-06 16:59 ` Andi Kleen
2011-05-06 17:09 ` Eric Dumazet
2011-05-06 17:17 ` Andi Kleen
2011-05-06 17:42 ` Eric Dumazet
2011-05-06 17:50 ` Andi Kleen
2011-05-06 19:26 ` Eric Dumazet
2011-05-06 20:04 ` Eric Dumazet
2011-05-06 20:24 ` john stultz
2011-05-06 22:30 ` Eric Dumazet
2011-05-06 22:46 ` john stultz
2011-05-06 23:00 ` Eric Dumazet
2011-05-06 23:28 ` john stultz
2011-05-07 5:02 ` Eric Dumazet
2011-05-07 7:11 ` Henrik Rydberg
2011-05-09 8:40 ` Thomas Gleixner
2011-05-12 9:13 ` [PATCH] seqlock: don't smp_rmb in seqlock reader spin loop, [PATCH] seqlock: don't smp_rmb in seqlock reader spin loop Milton Miller
2011-05-12 9:35 ` Eric Dumazet
2011-05-12 14:08 ` Andi Kleen
2011-05-06 20:18 ` [RFC] time: xtime_lock is held too long john stultz
2011-05-05 17:57 ` [PATCH] time: Add locking to xtime access in get_seconds() Andi Kleen
2011-05-05 20:17 ` john stultz
2011-05-05 20:24 ` Eric Dumazet
2011-05-05 20:40 ` john stultz
2011-05-05 20:43 ` Eric Dumazet
2011-05-05 20:56 ` Andi Kleen
2011-05-04 16:51 ` Max Asbock
2011-05-04 21:05 ` Andi Kleen
2011-05-04 23:05 ` john stultz
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