From: Chulmin Kim <cmkim@core.kaist.ac.kr>
To: linux-perf-users@vger.kernel.org
Subject: Question about LLC-load-misses event
Date: Mon, 15 Oct 2012 22:07:43 +0900 [thread overview]
Message-ID: <507C0A9F.8060405@core.kaist.ac.kr> (raw)
Hi, all.
I'm currently evaluating memory performance of my own machine (intel
x5650 cpu).
My machine can have NUMA configuration, but it is under control. (only
local mem access allowed)
As i run STREAM benchmark, i monitor LLC cache misses using "perf"
simultaneously.
(perf command : perf stat -a -A -e LLC-loads -e LLC-load-misses -e
instructions sleep 3)
The problem is,, the bandwidth from STREAM benchmark does not match with
the monitored value.
e.g.
I got 9395MB/s from Stream.
"perf" shows 134,642,063 LLC-load-misses for 3 seconds.
-> BW = ((# of events)/(3 seconds)) * 64 bytes / (1024*1024) = 2739MB/s
In this equation, the term (64bytes) is for cache line size, and the
term(1024*1024) is for (MB/s).
Why does this mismatch occur?
next reply other threads:[~2012-10-15 13:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-15 13:07 Chulmin Kim [this message]
2012-10-15 13:31 ` Question about LLC-load-misses event Chulmin Kim
2012-10-23 5:39 ` Namhyung Kim
2012-10-23 5:53 ` Chulmin Kim
2012-10-24 12:56 ` Chulmin Kim
-- strict thread matches above, loose matches on Subject: below --
2012-10-15 12:59 Chulmin Kim
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