linux-kernel - Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 28 Oct 2013 17:24:38 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Neil Horman <nhorman@...driver.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	linux-kernel@...r.kernel.org, sebastien.dugue@...l.net,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's


* Neil Horman <nhorman@...driver.com> wrote:

> Looking at the specific cpu counters we get this:
> 
> Base:
>      Total time: 0.179 [sec]
> 
>  Performance counter stats for 'perf bench sched messaging -- bash -c echo 1 > /sys/module/csum_test/parameters/test_fire' (20 runs):
> 
>        1571.304618 task-clock                #    5.213 CPUs utilized            ( +-  0.45% )
>             14,423 context-switches          #    0.009 M/sec                    ( +-  4.28% )
>              2,710 cpu-migrations            #    0.002 M/sec                    ( +-  2.83% )

Hm, for these second round of measurements were you using 'perf stat 
-a -C ...'?

The most accurate method of measurement for such single-threaded 
workloads is something like:

	taskset 0x1 perf stat -a -C 1 --repeat 20 ...

this will bind your workload to CPU#0, and will do PMU measurements 
only there - without mixing in other CPUs or workloads.

Thanks,

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