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Date: Sun, 16 Mar 2008 19:45:07 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
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()
Message-ID: <20080316184506.GW17940@kernel.dk>
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>
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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.

-- 
Jens Axboe