Re: parallelizing ipfw table

From: Andre Oppermann (andre_at_freebsd.org)
Date: 11/29/05

  • Next message: Stefan Bethke: "Re: proposal: TCP rendevous" 
    Date: Tue, 29 Nov 2005 16:36:01 +0100
To: Gleb Smirnoff <glebius@FreeBSD.org>

    Gleb Smirnoff wrote:
    > On Mon, Nov 28, 2005 at 06:04:50PM +0100, Max Laier wrote:
    > M> I remember that we had an extensive discussion about this around
    > M> FreeBSD-SA-05:13.ipfw - the bottom line seems to be: either parallel or
    > M> cacheing. Stack storage should work as well.
    >
    > The cacheing is a good idea when one table is looked up several times
    > for one packet. The above proposal eliminates need for such rulesets.
    > And thus we can work towards parallelizm.

    The ipfw tables are protected by the ipfw lock. So this parallel lookup
    Gelb has in his patch works fine and doesn't have any races.

    No caching between packets can be done without extra locks. Only caching
    between rules can be done by saving the result on the stack. The result
    must not be accessed anymore once the ipfw lock has been given up. 

    -- 
Andre
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