Re: sched_yield() makes OpenLDAP slow

[Howard Chu <hyc@symas.com>]

Nikita Danilov wrote:
> That returns us to the core of the problem: sched_yield() is used to
> implement a synchronization primitive and non-portable assumptions are
> made about its behavior: SUS defines that after sched_yield() thread
> ceases to run on the CPU "until it again becomes the head of its thread
> list", and "thread list" discipline is only defined for real-time
> scheduling policies. E.g., 
>
> int sched_yield(void)
> {
>        return 0;
> }
>
> and
>
> int sched_yield(void)
> {
>        sleep(100);
>        return 0;
> }
>
> are both valid sched_yield() implementation for non-rt (SCHED_OTHER)
> threads.
I think you're mistaken:
http://groups.google.com/group/comp.programming.threads/browse_frm/thread/0d4eaf3703131e86/da051ebe58976b00#da051ebe58976b00

sched_yield() is required to be supported even if priority scheduling is 
not supported, and it is required to cause the calling thread (not 
process) to yield the processor.

-- 
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc
  OpenLDAP Core Team            http://www.openldap.org/project/