Re: [Boost-bugs] [Boost C++ Libraries] #9856: [windows] condition_variable::wait_for returns wrong cv_status on timeout.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9856: [windows] condition_variable::wait_for returns wrong cv_status on timeout.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-02-01 01:41:22

#9856: [windows] condition_variable::wait_for returns wrong cv_status on timeout.
-------------------------+-------------------------------------------------
  Reporter:  pi88el@…    |      Owner:  ned14
      Type:  Bugs        |     Status:  new
 Milestone:              |  Component:  thread
   Version:  Boost       |   Severity:  Problem
  1.57.0                 |   Keywords:  condition_variable wait_for
Resolution:              |  cv_status
-------------------------+-------------------------------------------------

Comment (by ned14):

 Replying to [comment:19 viboes]:
 > It seems this is related to #10967 and #9720.

 It does appear that Windows respects the timeout you pass to a waitable
 timer, whilst it fuzzes any timeout given to WaitForMultipleObjects to be
 either too short or too long (on average 30% too long).

 BTW I have more empirical findings. It turns out Windows ignores all
 TolerableDelay values <= 26 ms. I have no idea why. But 27 ms is
 definitely the minimum for it to have any effect at all.

 Windows usually ticks at 15.6 ms, so a tolerable delay of 27 ms is about
 1.75 context switches. Do I have permission to set that minimum for all
 timers i.e.

 27 ms <= tolerable delay <= 5% of duration between now and timeout.

 Do we need an upper bound on tolerable delay? I can't see Windows running
 for ten seconds without at least one interrupt firing though ...

 Niall

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9856#comment:20>
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