Message-ID: <4664A5C6.7020004@de.ibm.com>
Date: Tue, 05 Jun 2007 01:52:38 +0200
From: Martin Peschke <mp3@de.ibm.com>
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To: Andrew Morton <akpm@linux-foundation.org>
CC: Adrian Bunk <bunk@stusta.de>, linux-kernel@vger.kernel.org
Subject: Re: 2.6.22-rc3-mm1: __attribute__((weak)) considered harmful
References: <20070530235823.793f00d9.akpm@linux-foundation.org> <20070602171425.GG5500@stusta.de> <20070604142212.c0b68d6a.akpm@linux-foundation.org>
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Andrew Morton wrote:
> On Sat, 2 Jun 2007 19:14:25 +0200
> Adrian Bunk <bunk@stusta.de> wrote:
> 
>> statistics-infrastructure-make-printk_clock-a-generic-kernel-wide-nsec-resolution.patch 
>> shows why __attribute__((weak)) is harmful because you don't see if a 
>> required non-weak implemtation is missing:
>>
>> In this case, the weak printk_clock() was renamed to timestamp_clock(), 
>> but the ARM and i386 implementations weren't renamed...
>>
> 
> printk_clock() is sched_clock() in disguise, and I'm not sure that making
> sched_clock() more widely available in this fashion is something that we
> want to do anyway.
> 
> Anyway, the statistics patches have just celebrated their first birthday
> and I don't see that they're getting sufficient momentum or interest to
> ever get into mainline so I think I'll drop them, sorry.

Andrew,
the lock contention statistics, which have been added to -mm recently, duplicate 
code that we have in the statistics patches. I think I can slim the lock 
tracking patches further down considerably (similar to my attempt at 
timerstats). I have a working prototype that is getting some polishing brushes. 
Would you like to wait how this goes?

As to timestamp_clock(): its useful for statistics, but still a minor feature. 
It would be unfortuante if that was the stumbling block for my patches. Am I 
right that the fix for the issue pointed at by Adrian is to rename those two 
occurrences of printk_clock()? Do you want me to submit a patch?

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