Re: perf tools miscellaneous questions

From: Francis Moreau
Date: Fri Nov 05 2010 - 08:38:25 EST


Victor Jimenez <victor.javier@xxxxxx> writes:

[...]

> If you are measuring last level cache misses, I would recommend you to
> use a memory intensive application/benchmark instead of /bin/true, as
> otherwise there can be a significant variation between two runs.

I agree.

But still with intensive application, I got the same results:


$ perf stat -r3 -e cache-misses:u gzip -9 -c vmlinux.o >/dev/null

Performance counter stats for 'gzip -9 -c vmlinux.o' (3 runs):

950704 cache-misses ( +- 24.925% )

82.619412905 seconds time elapsed ( +- 0.072% )


$ perf stat -r3 -e llc-load-misses:u,llc-store-misses:u gzip -9 -c vmlinux.o >/dev/null

Performance counter stats for 'gzip -9 -c vmlinux.o' (3 runs):

317054 LLC-load-misses ( +- 11.758% )
162634 LLC-store-misses ( +- 9.700% )

82.657099783 seconds time elapsed ( +- 0.167% )

Thanks
--
Francis
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/