linux-kernel - Re: [PATCH] WARN_ONCE(): use bool for condition

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Date:	Tue, 29 Sep 2009 20:18:10 -0300
From:	Cesar Eduardo Barros <cesarb@...arb.net>
To:	Cesar Eduardo Barros <cesarb@...arb.net>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, rolandd@...co.com, dwalker@...o99.com
Subject: Re: [PATCH] WARN_ONCE(): use bool for condition

Cesar Eduardo Barros escreveu:
> Andrew Morton escreveu:
>> On Sun, 27 Sep 2009 15:25:12 -0300
>> Cesar Eduardo Barros <cesarb@...arb.net> wrote:
>>
>>> Use the type bool for __ret_warn_once and __ret_warn_on, instead of int
>>> with a double negation. This matches the intent of the code better and
>>> should allow the compiler to generate better code, like in commit
>>> 70867453092297be9afb2249e712a1f960ec0a09. However, some versions of gcc
>>> seems to pessimize the code instead when the condition is not trivial.
>>
>> It would be nice if we had some accurate numbers on the kernel size
>> reductions from this, please.  I assume that the patch is still of
>> benefit in 2.6.32-rc1(2?), but it's always good to confirm.
> 
> In the first patch, Daniel Walker saw a decrease of 504 bytes in IA-32, 
> and I saw a decrease of 1462 bytes in x86-64 defconfig. I will resend it 
> 
> For this one, on the other hand, I am not sure whether it should be 
> included or dropped. While Daniel Walker saw a decrease of 84 bytes in 
> IA-32, I saw an *increase* of 598 bytes in x86-64 defconfig. It seems 

Forgot to mention, all my testing was against v2.6.31-9194-g0d9df25

-- 
Cesar Eduardo Barros
cesarb@...arb.net
cesar.barros@...il.com
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