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Date: Sun, 13 Oct 2002 00:50:05 -0700 (PDT)
Message-Id: <20021013.005005.41948345.davem@redhat.com>
To: wagnerjd@prodigy.net
Cc: robm@fastmail.fm, hahn@physics.mcmaster.ca, linux-kernel@vger.kernel.org,
       jhoward@fastmail.fm
Subject: Re: Strange load spikes on 2.4.19 kernel
From: "David S. Miller" <davem@redhat.com>
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	<000c01c2728d$263c0ca0$7443f4d1@joe>
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   From: "Joseph D. Wagner" <wagnerjd@prodigy.net>
   Date: Sun, 13 Oct 2002 02:49:55 -0500

   > But there is no fundamental reason for that, we just haven't
   > gotten around to threading that bit yet.
   
   Oh yes there is.  What if an allocation of blocks and/or inodes is
   preempted?  Another thread could attempt to allocate the same set of
   blocks and/or inodes.
   
That's why we protect the allocation with SMP locking primitives
which under Linux prevent preemption.

This isn't rocket science, the IP networking is fully threaded for
example and I consider that about as hard to thread as something like
ext2/ext3 inode/block allocation.

Also, as Andi Kleen noted, it's actually filesystem dependant whether
the inode/block allocation is threaded or not.
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