Re: potential re change for 5.3?

From: Scott Long (scottl_at_samsco.org)
Date: 08/26/04

  • Next message: Poul-Henning Kamp: "Re: potential re change for 5.3?" 
    Date: Wed, 25 Aug 2004 23:33:55 -0600
To: Poul-Henning Kamp <phk@phk.freebsd.dk>

    Poul-Henning Kamp wrote:
    > In message <412D0868.9060203@freebsd.org>, Scott Long writes:
    >
    >
    >>I'm not suggesting anything different, just making a note of something
    >>that might be desirable in the future. In a way, I see GEOM as having
    >>the potential to be like Netgraph where it intercepts operations that it
    >>wants to process through it's framework and lets ones that it doesn't
    >>pass directly through without a decoupling through extra kernel threads.
    >>But that's only one possible strategy. Introducing the concept of a
    >>I/O scheduler that spawns KSE's to handle individual I/O requests is
    >>another possibility.
    >
    >
    > Well, the problem here is that requests which cannot be dealt with
    > due to resource shortages should be queued at the level where they
    > require least resources. A request queued inside a driver holds
    > far more resources than a request in the pure bio format at the
    > entrance to the driver for instance.

    Not necessarily. It's not hard for a driver to keep a request queued on
    the bioq and not consume and driver resources at all.

    >
    > And spawning KSE's in low memory situations is a recipe for suicide.
    >

    Probably true.

    Scott
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