Re: [PATCH] posix clocks: replace mutex with reader/writer semaphore

[Richard Cochran <richardcochran@gmail.com>]

On Wed, Mar 30, 2011 at 03:41:40PM +0200, Thomas Gleixner wrote:
> On Wed, 30 Mar 2011, Richard Cochran wrote:
> 
> > A dynamic posix clock is protected from asynchronous removal by a mutex.
> > However, using a mutex has the unwanted effect that a long running clock
> > operation in one process will unnecessarily block other processes.
> > 
> > For example, one process might call read() to get an external time stamp
> > coming in at one pulse per second. A second process calling clock_gettime
> > would have to wait for almost a whole second.
> > 
> > This patch fixes the issue by using a reader/writer semaphore instead of
> > a mutex.
> 
> Yuck. /me wonders why we did not see that during the review :)

Thomas,

I don't see this in -rc3, but I think it should go in.
Can you please take this one?

Thanks,

Richard