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Date:      Thu, 26 Jan 2006 21:15:02 -0600
From:      "Christian S.J. Peron" <csjp@FreeBSD.org>
To:        Jason Evans <jasone@FreeBSD.ORG>
Cc:        cvs-src@FreeBSD.ORG, src-committers@FreeBSD.ORG, Andrey Chernov <ache@FreeBSD.ORG>, cvs-all@FreeBSD.ORG
Subject:   Re: cvs commit: src/lib/libc/stdlib malloc.c
Message-ID:  <43D99036.3010102@FreeBSD.org>
In-Reply-To: <6B47D688-0A7D-421F-9830-9493EC375307@FreeBSD.ORG>
References:  <200601270236.k0R2ai2x067283@repoman.freebsd.org> <20060127025150.GA57825@nagual.pp.ru> <6B47D688-0A7D-421F-9830-9493EC375307@FreeBSD.ORG>

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Jason Evans wrote:

> On Jan 26, 2006, at 6:51 PM, Andrey Chernov wrote:
>
>> I worry about my system performance. Could you please make all  
>> statistics
>> and debug code conditional, debending on some flags which could be  
>> set as
>> malloc options? Even in case this is a test period now, some people
>> perhaps don't want some tests. It is much easy to turn some tests  
>> off via
>> malloc options than to comment out manually corresponding malloc.c  
>> defines
>> after each cvsup.
>
>
> Unfortunately, run-time checks for the debugging features are  
> expensive, since the debugging code is scattered throughout  
> malloc.c.  This pretty much mandates compile-time configuration, for  
> performance reasons.
>
> I can disable statistics and debugging, if there's a general  
> consensus to do so.  How much performance difference is the debug/ 
> stats code making for you?  I've only been disabling debug/stats for  
> benchmarking purposes, so I don't have a good feel for how much it  
> impacts overall system performance.


These malloc debugging/stats features have been invaluable. I vote to 
accept the performance hit in exchange for useful debugging/stats 
features in -CURRENT, and disable them in -STABLE/-RELEASE when they are 
ready.

-- 
Christian S.J. Peron
csjp@FreeBSD.ORG
FreeBSD Committer
FreeBSD Security Team




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