linux-kernel - Re: [PACH] smp: uninline num_online_cpus() & num_possible

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Date:	Tue, 09 Dec 2008 07:36:00 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PACH] smp: uninline num_online_cpus() & num_possible_cpus()

Rusty Russell a écrit :
> On Saturday 06 December 2008 04:03:44 Eric Dumazet wrote:
>> num_online_cpus() and num_possible_cpus() are not performance
>> critical and are quite large.
>>
>> Unlining them shrinks kernel text size by 7523 bytes on x86,
>> if NR_CPUS>32
> 
> Hi Eric!
> 
>   Slight misdiagnosis, I think.  One base problem is addressed in fixing
> the bitmap operators (see "[PATCH] bitmap: test for constant as well as
> small size for inline versions" on lkml Message-Id: <200811160907.07140.rusty@...tcorp.com.au>).  This is already in
> linux-next, and I've pasted it below.
> 
>   Worse, you used the obsolete cpumask operators :)
> 

I see ! Good work ;)

So the gain would be 11 bytes per call site, and about one hundred calls,
maybe not worth it :)

Thanks


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