[PATCH 0/3] Discourage sched_yield(2)

[Alejandro Colomar <alx.manpages@gmail.com>]

Hi Andrew,

Here's a patch set for discouraging sched_yield(2).  See the formatted
page at the bottom.  I also updated some POSIX historic detail.

Cheers,
Alex


Alejandro Colomar (3):
  sched_yield.2: HISTORY: POSIX.1-2008 makes this non-optional
  sched_yield.2: NOTES: Remove misleading sentence
  sched_yield.2: Rename NOTES to CAVEATS, and reorder contents

 man2/sched_yield.2 | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

---
$ MANWIDTH=72 man ./man2/sched_yield.2 | cat
sched_yield(2)            System Calls Manual           sched_yield(2)

NAME
       sched_yield - yield the processor

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <sched.h>

       int sched_yield(void);

DESCRIPTION
       sched_yield()  causes the calling thread to relinquish the CPU.
       The thread is moved to the end of the queue for its static pri‐
       ority and a new thread gets to run.

RETURN VALUE
       On success, sched_yield() returns 0.  On error, -1 is returned,
       and errno is set to indicate the error.

ERRORS
       In the Linux implementation, sched_yield() always succeeds.

STANDARDS
       POSIX.1‐2008.

HISTORY
       POSIX.1‐2001 (but optional).  POSIX.1‐2008.

       Before POSIX.1‐2008, systems on which sched_yield()  is  avail‐
       able defined _POSIX_PRIORITY_SCHEDULING in <unistd.h>.

CAVEATS
       sched_yield()  is  intended  for  use with real‐time scheduling
       policies (i.e., SCHED_FIFO or SCHED_RR).  Use of  sched_yield()
       with  nondeterministic  scheduling policies such as SCHED_OTHER
       is unspecified and very likely means your application design is
       broken.

       If the calling thread is the only thread in the highest  prior‐
       ity  list at that time, it will continue to run after a call to
       sched_yield().

       Avoid calling sched_yield()  unnecessarily  or  inappropriately
       (e.g.,  when  resources needed by other schedulable threads are
       still held by the caller), since doing so will result in unnec‐
       essary context switches, which will degrade system performance.

SEE ALSO
       sched(7)

Linux man‐pages (unreleased)    (date)                  sched_yield(2)
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2.40.1