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From: Jeff Roberson <jeff@FreeBSD.org>
Date: Tue, 2 Oct 2007 01:30:18 +0000 (UTC)
To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org
X-FreeBSD-CVS-Branch: HEAD
Cc: 
Subject: cvs commit: src/sys/kern sched_ule.c
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jeff        2007-10-02 01:30:18 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             sched_ule.c 
  Log:
   - Reassign the thread queue lock to newtd prior to switching.  Assigning
     after the switch leads to a race where the outgoing thread still owns
     the local queue lock while another cpu may switch it in.  This race
     is only possible on machines where cpu_switch can take significantly
     longer on different cpus which in practice means HTT machines with
     unfair thread scheduling algorithms.
  
  Found by:       kris (of course)
  Approved by:    re
  
  Revision  Changes    Path
  1.212     +6 -4      src/sys/kern/sched_ule.c