linux-kernel - Re: [PATCH 3/3] perf: bench: fix memcpy/memset output

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Date:	Mon, 8 Dec 2014 11:25:33 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Rabin Vincent <rabin.vincent@...s.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org, rabin@....in,
	Rabin Vincent <rabinv@...s.com>
Subject: Re: [PATCH 3/3] perf: bench: fix memcpy/memset output


* Rabin Vincent <rabin.vincent@...s.com> wrote:

> The memcpy and memset benchmarks return bogus results when iterations >
> 0 because the iterations value is not taken into account when
> calculating the final result:
> 
>  $ perf bench mem memset --only-prefault --length 1GB --iterations 1
>  # Running 'mem/memset' benchmark:
>  # Copying 1GB Bytes ...
> 
>        20.798669 GB/Sec (with prefault)
>  $ perf bench mem memset --only-prefault --length 1GB --iterations 10
>  # Running 'mem/memset' benchmark:
>  # Copying 1GB Bytes ...
> 
>         2.086576 GB/Sec (with prefault)
>  $ perf bench mem memset --only-prefault --length 1GB --iterations 100
>  # Running 'mem/memset' benchmark:
>  # Copying 1GB Bytes ...
> 
>       212.840917 MB/Sec (with prefault)
> 
> Fix this.
> 
> Signed-off-by: Rabin Vincent <rabin.vincent@...s.com>

Acked-by: Ingo Molnar <mingo@...nel.org>

Thanks,

	Ingo
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