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Date: Sun, 16 Mar 2008 15:58:44 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: Jens Axboe <jens.axboe@oracle.com>
CC: linux-kernel@vger.kernel.org, npiggin@suse.de, dgc@sgi.com
Subject: Re: [PATCH 1/7] x86-64: introduce fast variant of smp_call_function_single()
References: <1205322940-20127-1-git-send-email-jens.axboe@oracle.com> <1205322940-20127-2-git-send-email-jens.axboe@oracle.com> <47DAC21C.1040805@goop.org> <20080316184506.GW17940@kernel.dk>
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Jens Axboe wrote:
> On Fri, Mar 14 2008, Jeremy Fitzhardinge wrote:
>   
>> Jens Axboe wrote:
>>     
>>> rom: Nick Piggin <npiggin@suse.de>
>>>  
>>>       
>> Why is this necessary?  How is smp_call_function_single slow?
>>     
>
> Because it's completely serialized by the call_lock spinlock.
>   

Hm, yes.  Would it be possible to implement smp_call_function_mask in a 
generic way to avoid that?  Turn the static structure into a per-cpu 
request list?

    J