Re: Removing kernel thread stack swapping

From: Stephan Uphoff (ups_at_tree.com)
Date: 03/16/05

  • Next message: Don Lewis: "Re: Freeing vnodes." 
    To: Peter Wemm <peter@wemm.org>
Date: Tue, 15 Mar 2005 22:19:43 -0500

    On Tue, 2005-03-15 at 20:43, Peter Wemm wrote:
    > On Thursday 03 March 2005 07:35 am, David Schultz wrote:
    > > On Thu, Mar 03, 2005, John Baldwin wrote:
    > [..]
    > > > Hence, don't kill this whole feature just because someone is too
    > > > lazy to fix a bug.
    > >
    > > Fair enough. I'll defer to you on the extent of the problem.
    > > David seemed to think that it was more widespread. (BTW, does
    > > *anyone* know what the PHOLD() in kern_physio is for? Is it a
    > > holdover from when the PCB was in struct user?)
    >
    > I've wondered about this myself in the past. I went looking once and
    > discovered that it never did anything that I could find. I believe it
    > is a case of 'because it was always done that way' or because the
    > pseudocode in the Bach or bsd books had it. There is certainly no
    > functional need for it in FreeBSD.

    kern_physio prevents chunks of memory needed for IO from being paged
    out. Swapping out a thread in kern_physio will prevent it from releasing
    the resources soon. With minphys > stack size I think PHOLD() is still a
    good idea.

    Stephan

    _______________________________________________
    freebsd-arch@freebsd.org mailing list
    http://lists.freebsd.org/mailman/listinfo/freebsd-arch
    To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org"

  • Next message: Don Lewis: "Re: Freeing vnodes."