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From: Franck Bui-Huu <vagabon.xyz@gmail.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        linux-kernel@vger.kernel.org, 2nddept-manager@sdl.hitachi.co.jp
Subject: Re: [PATCH] perf-probe: no need to initialize the entire temporary buffers in synthesize_perf_probe_point()
References: <m3wrn07blu.fsf@gmail.com> <4D142591.2030101@hitachi.com>
Date: Mon, 27 Dec 2010 22:01:44 +0100
In-Reply-To: <4D142591.2030101@hitachi.com> (Masami Hiramatsu's message of
	"Fri, 24 Dec 2010 13:46:09 +0900")
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Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> writes:

> (2010/12/24 0:27), Franck Bui-Huu wrote:
>> From: Franck Bui-Huu <fbuihuu@gmail.com>
>> 
>> This patches only put a single null byte at the beginning of each
>> temporary buffers line[], offs[], file[] instead of filling their full
>> contents with null bytes.
>
> Hmm, sorry but NAK it.
>

No problem :)

>
> IMHO, with modern chips, the original code has no problem from the
> viewpoint of memory access (all are cached and no need to access just
> one byte) nor a bottleneck.

I'm not sure to understand this.

But my point is that you're clearing the whole buffers with 0 although
you just need to initialize them with the null string (a single null
byte at the beginning).

So you're doing useless memory accesses (cached or not).

I agree with you that it won't make any speed improvements though, but
it was just clearer for me, since what you want are null strings and not
a char arrays fill with 0.

Thanks.
-- 
		Franck
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