lkml.org 
[lkml]   [2005]   [Dec]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH 1/19] MUTEX: Introduce simple mutex implementation
    From
    On Sat, Dec 17, 2005 at 04:43:05PM -0700, Matthew Wilcox wrote:
    > I have a better example of something we currently get wrong that I
    > haven't heard any RT person worry about yet. If two tasks are sleeping
    > on the same semaphore, the one to be woken up will be the first one to
    > wait for it, not the highest-priority task.
    >
    > Obviously, this was introduced by the wake-one semantics. But how to
    > fix it? Should we scan the entire queue looking for the best task to
    > wake? Should we try to maintain the wait list in priority order? Or
    > should we just not care? Should we document that we don't care? ;-)

    -rt deals with this using priority sorted wait queue and direct ownership
    hand off to the woken thread. It's working fine for now, but things like
    wake-all and company should probably be explored for various uses. A
    strict general purpose and RT usage of the Linux kernel have different
    performance characteristic and mutex selection at compile time should
    address things precisely.

    bill

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-12-22 13:33    [W:0.020 / U:1.120 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site