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Subject: Re: sched_yield() makes OpenLDAP slow
From: Lee Revell <rlrevell@joe-job.com>
To: Howard Chu <hyc@symas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>, Robert Hancock <hancockr@shaw.ca>,
       linux-kernel <linux-kernel@vger.kernel.org>
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Date: Sat, 20 Aug 2005 17:50:01 -0400
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On Sat, 2005-08-20 at 11:38 -0700, Howard Chu wrote:
> Nick Piggin wrote:
> >  Robert Hancock wrote:
> > > I fail to see how sched_yield is going to be very helpful in this
> > > situation. Since that call can sleep from a range of time ranging
> > > from zero to a long time, it's going to give unpredictable results.
> 
> >  Well, not sleep technically, but yield the CPU for some undefined
> >  amount of time.
> 
> Since the slapd server was not written to run in realtime, nor is it 
> commonly run on realtime operating systems, I don't believe predictable 
> timing here is a criteria we care about. One could say the same of 
> sigsuspend() by the way - it can pause a process for a range of time 
> ranging from zero to a long time. Should we tell application writers not 
> to use this function either, regardless of whether the developer thinks 
> they have a good reason to use it?

Of course not.  We should tell them that if they use sigsuspend() they
cannot assume that the process will not wake up immediately.

Lee