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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2017-10-02 22:36:50 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2017-10-20 10:20:48 +0200 |
| commit | 2dea72418db7f44f71018b9228bbcf8d80c38ad4 (patch) | |
| tree | 2fc8bba605771d62508856015de411f8a52b1f8d /man3/pthread_spin_init.3 | |
| parent | 41041696d3bb135aa72aee029e3f5ad35539ec1a (diff) | |
| download | man-pages-2dea72418db7f44f71018b9228bbcf8d80c38ad4.tar.gz | |
pthread_spin_init.3: Spin locks should be used with real-time scheduling policies
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Diffstat (limited to 'man3/pthread_spin_init.3')
| -rw-r--r-- | man3/pthread_spin_init.3 | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/man3/pthread_spin_init.3 b/man3/pthread_spin_init.3 index af9a926718..9d43fd035e 100644 --- a/man3/pthread_spin_init.3 +++ b/man3/pthread_spin_init.3 @@ -114,6 +114,19 @@ POSIX.1-2001. .PP Support for process-shared spin locks is a POSIX option. The option is supported in the glibc implementation. +.SH NOTES +Spin locks should be employed in conjunction with +real-time scheduling policies +.RB ( SCHED_FIFO , +or possibly +.BR SCHED_RR ). +Use of spin locks with nondeterministic scheduling policies such as +.BR SCHED_OTHER +probably indicates a design mistake. +The problem is that if a thread operating under such a policy +is scheduled off the CPU while it holds a spin lock, +then other threads will waste time spinning on the lock +until the lock holder is once more rescheduled and releases the lock. .SH SEE ALSO .ad l .nh |