Re: potential re change for 5.3?

From: Poul-Henning Kamp (phk_at_phk.freebsd.dk)
Date: 08/26/04

  • Next message: Scott Long: "Re: potential re change for 5.3?" 
    To: Scott Long <scottl@freebsd.org>
Date: Thu, 26 Aug 2004 07:33:05 +0200

    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.

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

    -- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
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  • Next message: Scott Long: "Re: potential re change for 5.3?"

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