From: Andi Kleen <firstname.lastname@example.org>
Sent: Saturday, September 17, 2011 10:44 PM
Subject: Re: oprofile sample rate
Jeff Eastlack <email@example.com
> This sets the sample rate at 10k.
> 1) does this mean it samples at 10k clock cycles or 10k ticks or
It samples every 10k events.
> 2) what does a sample mean. The way I
understand performance counters
A sample means 10k events occurred.
> that they count the occurrence of a specific event regardless of what
> program caused it ... right? How does oprofile "sample" an event that
> might have occurred several times in between the sample rate and assign
> that sample to a program?
It's all statistical with an sampling error and the hope that large
numbers fix it up. In addition there's usually some "skid": samples
somewhat later than the actual event. In many cases that's fine, in
others it can cause systematic mis-sampling.
-- Speaking for myself only