From: David Mosberger <davidm@napali.hpl.hp.com>
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Message-ID: <16483.37151.114594.263358@napali.hpl.hp.com>
Date: Thu, 25 Mar 2004 18:10:39 -0800
To: Andrew Morton <akpm@osdl.org>
Cc: davidm@hpl.hp.com, davidm@napali.hpl.hp.com, mpm@selenic.com,
       linux-kernel@vger.kernel.org
Subject: Re: Fw: potential /dev/urandom scalability improvement
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>>>>> On Thu, 25 Mar 2004 18:00:14 -0800, Andrew Morton <akpm@osdl.org> said:

  Andrew> We may as well stick prefetch_range() in prefetch.h.

Fair enough.

  Andrew> And Matt's patch series is not a thing I want to take on
  Andrew> board at present, so let's stick with the straight
  Andrew> scalability patch for now.

  Andrew> I moved the prefetch_range() call to outside the spinlock.
  Andrew> Does that make sense?

The other CPUs will dirty that data, so prefetching it before you hold
the lock is almost certainly bad for performance.  (Well, to be
precise, it really depends on the number of lines dirtied.)

	--david
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