[lkml]   [2007]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH] flush_cpu_workqueue: don't flush an empty ->worklist
    On Tue, 9 Jan 2007 10:34:17 +0530
    Srivatsa Vaddagiri <> wrote:

    > On Mon, Jan 08, 2007 at 03:54:28PM -0800, Andrew Morton wrote:
    > > Furthermore I don't know which of these need to be tossed overboard if/when
    > > we get around to using the task freezer for CPU hotplug synchronisation.
    > > Hopefully, a lot of them. I don't really understand why we're continuing
    > > to struggle with the existing approach before that question is settled.
    > Good point!
    > Fundamentally, I think we need to answer this question:
    > "Do we provide *some* mechanism to block concurrent hotplug operations
    > from happening? By hotplug operations I mean both changes to the bitmap
    > and execution of all baclbacks in CPU_DEAD/ONLINE etc"
    > If NO, then IMHO we will be forever fixing races
    > If YES, then what is that mechanism? freeze_processes()? or a magical
    > lock?
    > freeze_processes() cant be that mechanism, if my understanding of it is
    > correct - see

    That's not correct. freeze_processes() will freeze *all* processes. All
    of them are forced to enter refrigerator(). With the mysterious exception
    of some I/O-related kernel threads, which might need some thought.

    > and

    Am not sure how that's related.

    > I would be happy to be corrected if the above impression of
    > freeze_processes() is corrected ..

    It could be that the freezer needs a bit of work for this application.
    Obviously we're not interested in the handling of disk I/O, so we'd really
    like to do a simple
    try_to_freeze_tasks(FREEZER_USER_SPACE|FREEZER_KERNEL_THREADS), but the
    code isn't set up to do that (it should be). The other non-swsusp callers
    probably want this change as well. But that's all a minor matter.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-01-09 07:21    [W:0.022 / U:17.664 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site