[lkml]   [2006]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: NPTL mutex and the scheduling priority
    On Tue, 2006-06-13 at 04:48 -0400, Jakub Jelinek wrote:
    > On Mon, Jun 12, 2006 at 05:24:28PM +0200, S?bastien Dugu? wrote:
    > > The patch you refer to is at
    > >
    > >
    > > But maybe a better solution for condvars would be to implement
    > > something like a futex_requeue_pi() to handle the broadcast and
    > > only use PI futexes all along in glibc.
    > FUTEX_REQUEUE certainly should be able to requeue from normal futex
    > to a PI futex or vice versa, I don't think it is desirable to create
    > a separate futex cmds for that.

    Indeed, that would be preferable but might get tricky.

    > Now not sure what do you mean by "use PI futexes all along in glibc",
    > certainly you don't mean using them for normal mutexes, right?
    > FUTEX_LOCK_PI has effects the normal futexes shouldn't have.
    > The condvars can be also used with PP mutexes and using PI for the cv
    > internal lock unconditionally wouldn't be the right thing either.

    I effectively meant using a PI futex for the cv __data.__futex but now
    I realize it's a Really Bad Idea.

    To summarize (correct me if I'm wrong), we need a way in the broadcast
    case to promote the cv __data.__futex type to the type of the external
    mutex (PI, PP, normal) in the requeue path. Therefore we need the
    ability to requeue waiters on a regular futex onto a PI futex.

    Ingo, Thomas, is this feasible?


    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: 2006-06-13 14:02    [W:0.024 / U:2.796 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site