From: David Ahern <dsahern@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>,
"linux-perf-use." <linux-perf-users@vger.kernel.org>
Subject: Re: Weird instruction profiling
Date: Wed, 18 Feb 2015 16:46:25 -0700 [thread overview]
Message-ID: <54E52451.4030303@gmail.com> (raw)
In-Reply-To: <20150218233836.GB823@two.firstfloor.org>
On 2/18/15 4:38 PM, Andi Kleen wrote:
> On Wed, Feb 18, 2015 at 04:33:31PM -0700, David Ahern wrote:
>> On 2/18/15 11:30 AM, Andi Kleen wrote:
>>
>>>> I think Andi mentioned this to me last year -- that instruction
>>>> profiling was no longer reliable.
>>>
>>> It never was.
>>
>> Why is that? What about profiling with other hardware counters?
>
> Practically all profiling has skid of some form.
ok, so you meant that only in the context of skid meaning the hit
instruction is off a few (ie., squint backwards at the annotate output).
David
next prev parent reply other threads:[~2015-02-18 23:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-18 9:57 Weird instruction profiling Brendan Gregg
2015-02-18 18:30 ` Andi Kleen
2015-02-18 23:33 ` David Ahern
2015-02-18 23:38 ` Andi Kleen
2015-02-18 23:46 ` David Ahern [this message]
2015-02-20 19:04 ` Brendan Gregg
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