Re: [patch] lazy I/O bitmap copy for i386 (ver 2) ...

From: Ingo Molnar (mingo_at_elte.hu)
Date: 08/31/04

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    Date:	Tue, 31 Aug 2004 14:06:11 +0200
To: Davide Libenzi <davidel@xmailserver.org>

    * Davide Libenzi <davidel@xmailserver.org> wrote:

    > The following patch implements the lazy I/O bitmap copy for the i386
    > architecture. It uses an invalid bitmap offset inside the TSS to
    > eventually handle the correct bitmap update in the GPF handler. The
    > logic is the same of the first version, plus the usage of
    > get/put_cpu() (thx Brian) and the nesting over the latest Ingo
    > variable bitmap bits.

    your patch looks good to me. I believe the killer argument is what you
    mentioned previously, that a single GFP is cheaper than a single I/O op,
    so even the worst-case (an I/O app doing precisely one I/O op during its
    scheduling atom - very unlikely) shouldnt degrade all that much. The
    patch is a speedup in every other case.

    Signed-off-by: Ingo Molnar <mingo@elte.hu>

            Ingo
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