Re: Sysinstall automatic filesystem size generation.

From: Don Lewis (truckman_at_FreeBSD.org)
Date: 08/30/05

  • Next message: Nate Lawson: "Re: 5-STABLE cpufreq hotter than est from ports" 
    Date: Mon, 29 Aug 2005 20:36:41 -0700 (PDT)
To: jd@ugcs.caltech.edu

    On 29 Aug, Jon Dama wrote:

    > It seems you need to add a layer of indirection. (owing to biodone being
    > called merely when the drive has cached the request). What you know is
    > that those operations marked completed by biodone are in fact done only
    > after a (costly) flush cache operation is executed.
    >
    > Therefore you want to delay this operation for as long as possible, in
    > fact until you actually depend on biodone being honest. I.e., at the time
    > another operation is inserted into the WORKLIST.
    >
    > The secret I think is to keep track of which bp's marked B_DONE by
    > biodone that have been certified by a flush cache. Thus permitting you to
    > avoid some cache flushes. Furthermore, the softdep code has to be
    > responsible for envoking the flush cache operation when it notices that
    > the B_DONE flag that it cares about does not have a matching
    > B_REALLY_DONE flag, which every block should have that had B_DONE set
    > before the flush cache operation happened.

    I believe you are correct.

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