Re: Strange load spikes on 2.4.19 kernel

From: David S. Miller (davem@redhat.com)
Date: Sun Oct 13 2002 - 02:50:05 EST


   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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