On Mar 7 16:19, Dan Bonachea wrote: > I suspect I may have discovered a corner-case performance bug in > Cygwin's pthread_create() implementation. The problem arises when a > call to pthread_create() is made concurrently with multiple pthreads > in the same process spinning on calls to sched_yield(). I've searched > the Cygwin mailing list archives, user guide, FAQ, and Google and not > found any mention of this particular misbehavior. > > A minimal demo program is copied below and also available here: > https://upc-bugs.lbl.gov/bugzilla/attachment.cgi?id=549 > The demo program is a narrowed-down version of test code used in the > GASNet communication system (http://gasnet.lbl.gov). > > The test code calls pthread_create to spawn a user-controlled number > of threads, which then execute 1000 "spin barriers" - implemented by > spinning on in-memory flags and stalling with sched_yield(). The test > can also optionally insert a pthread_barrier_wait() across all threads > before the first spin barrier.
Thanks for the thorough analysis and especially the testcase! I applied a fix for this problem and uploaded new developer snapshots to https://cygwin.com/snapshots/ Please give them a try. Thanks, Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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