From: Ingo Molnar <mingo@elte.hu>
To: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Lin Ming <ming.m.lin@intel.com>,
Stephane Eranian <eranian@google.com>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] perf, x86: Add Intel Nehalem/Westmere uncore pmu
Date: Wed, 6 Jul 2011 11:35:01 +0200 [thread overview]
Message-ID: <20110706093501.GA11969@elte.hu> (raw)
In-Reply-To: <cf54fbb6e05ab86a5c6029eda70012e4.squirrel@www.firstfloor.org>
* Andi Kleen <andi@firstfloor.org> wrote:
>
> >
> >> But it's not strictly required I would say,
> >> 44(?) bits are probably enough for near all use cases.
> >
> > 44bits is in the hours range for pure cycle counts, which is
> > so-so. I bet you're going to be very annoyed when you find your
> > counters are wrecked after your 5 hour test run finishes.
>
> For these kinds of long running measurements you usually care about
> ratios, not absolutes. Some infrequent wrapping should not
> substantially change. those.
That's just empty blathering - those who *do* take a look at
long-running absolute values obviously care.
There's absolutely no reason to be sloppy here - this needs to be
implemented correctly.
Thanks,
Ingo
next prev parent reply other threads:[~2011-07-06 9:35 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-30 8:09 [PATCH 0/4] perf: Intel uncore pmu counting support Lin Ming
2011-06-30 8:09 ` [PATCH 1/4] perf, x86: Add Intel Nehalem/Westmere uncore pmu Lin Ming
2011-06-30 14:08 ` Peter Zijlstra
2011-07-01 6:05 ` Lin Ming
2011-06-30 16:58 ` Andi Kleen
2011-07-04 6:39 ` Lin Ming
2011-07-04 8:38 ` Peter Zijlstra
2011-07-04 21:57 ` Andi Kleen
2011-07-05 11:22 ` Peter Zijlstra
2011-07-05 12:48 ` Lin Ming
2011-07-05 12:56 ` Peter Zijlstra
2011-07-05 13:13 ` Lin Ming
2011-07-05 16:01 ` Andi Kleen
2011-07-06 9:35 ` Ingo Molnar [this message]
2011-06-30 8:09 ` [PATCH 2/4] perf, x86: Add Intel SandyBridge " Lin Ming
2011-06-30 22:09 ` Peter Zijlstra
2011-06-30 8:09 ` [PATCH 3/4] perf: Remove perf_event_attr::type check Lin Ming
2011-07-21 19:31 ` [tip:perf/core] " tip-bot for Lin Ming
2011-06-30 8:09 ` [PATCH 4/4] perf tool: Get PMU type id from sysfs Lin Ming
2011-06-30 12:10 ` [PATCH 0/4] perf: Intel uncore pmu counting support Stephane Eranian
2011-06-30 14:10 ` Peter Zijlstra
2011-06-30 16:27 ` Stephane Eranian
2011-07-01 3:17 ` Lin Ming
2011-07-01 10:49 ` Stephane Eranian
2011-07-01 12:23 ` Stephane Eranian
2011-07-01 12:28 ` Stephane Eranian
2011-07-04 6:03 ` Lin Ming
2011-07-01 5:49 ` Lin Ming
2011-07-01 11:08 ` Ingo Molnar
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