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

[Thomas Gleixner]

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 :)
 
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