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]

Message-ID: <20131029112022.GA24477@neilslaptop.think-freely.org>
Date:	Tue, 29 Oct 2013 07:20:22 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Ingo Molnar <mingo@...nel.org>
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

On Tue, Oct 29, 2013 at 09:25:42AM +0100, Ingo Molnar wrote:
> 
> * Neil Horman <nhorman@...driver.com> wrote:
> 
> > Heres my data for running the same test with taskset restricting 
> > execution to only cpu0.  I'm not quite sure whats going on here, 
> > but doing so resulted in a 10x slowdown of the runtime of each 
> > iteration which I can't explain.  As before however, both the 
> > parallel alu run and the prefetch run resulted in speedups, but 
> > the two together were not in any way addative.  I'm going to keep 
> > playing with the prefetch stride, unless you have an alternate 
> > theory.
> 
> Could you please cite the exact command-line you used for running 
> the test?
> 
> Thanks,
> 
> 	Ingo
> 

Sure it was this:
for i in `seq 0 1 3`
do
echo $i > /sys/module/csum_test/parameters/module_test_mode
taskset -c 0 perf stat --repeat 20 -C 0 -ddd perf bench sched messaging -- /root/test.sh
done >> counters.txt 2>&1

where test.sh is:
#!/bin/sh
echo 1 > /sys/module/csum_test/parameters/test_fire


As before, module_test_mode selects a case in a switch statement I added in
do_csum to test one of the 4 csum variants we've been discusing (base, prefetch,
parallel ALU or both), and test_fire is a callback trigger I use in the test
module to run 100000 iterations of a checksum operation.  As you requested, I
ran the above on cpu 0 (-C 0 on perf and -c 0 on taskset), and I removed all irq
affinity to cpu 0.

Regards
Neil

--
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/