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DragonFly kernel List (threaded) for 2005-06
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From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 2 Jun 2005 10:33:06 -0700 (PDT)

:Matt, I don't think this is a good to rush. I think it can seriously degrade
:performance, esp. since some of the spl() protections are hold over longer
:areas of time.
:I don't have a problem with replacing critical short usage areas with
:critical sections, but flatting it directly is not good.

    Joerg, we've been juggling the SPL issue since day 1.  The time has come
    to remove them.

    And, again, I completely disagree with your performance concerns.  I
    challenge you to find a case where performance would be degraded.
    The most widely used long-held SPLs in the system are SPLBIO and SPLVM,
    and guess what?  They pretty much mask ALL MAJOR DEVICES anyway.  So
    what's the point of having a variable mask in the first place?  No
    point at all...

    Even more importantly, many of these spl/critical-sections are going to
    eventually be replaced by serialization in order to become MP safe and
    remove Giant.  So even if there were some performance degredation (and
    there won't be), it's a moot point.  We need to remove the SPLs to 
    be able to progress.

					Matthew Dillon 

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