Date: Sun, 18 Mar 2012 17:56:02 -0700 From: Julian Elischer <julian@freebsd.org> To: Pawel Jakub Dawidek <pjd@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, David Xu <davidxu@freebsd.org> Subject: Re: svn commit: r232209 - in head: lib/libthr/thread sys/kern Message-ID: <4F668422.1000308@freebsd.org> In-Reply-To: <20120318185014.GK1340@garage.freebsd.pl> References: <201202271338.q1RDcqEQ020033@svn.freebsd.org> <20120318185014.GK1340@garage.freebsd.pl>
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On 3/18/12 11:50 AM, Pawel Jakub Dawidek wrote: > On Mon, Feb 27, 2012 at 01:38:52PM +0000, David Xu wrote: >> Author: davidxu >> Date: Mon Feb 27 13:38:52 2012 >> New Revision: 232209 >> URL: http://svn.freebsd.org/changeset/base/232209 >> >> Log: >> Follow changes made in revision 232144, pass absolute timeout to kernel, >> this eliminates a clock_gettime() syscall. > This or some other change has broken CLOCK_MONOTONIC usage with > condition variables. > > You should be able to reproduce this by something like this: > > pthread_cond_t cv; > pthread_condattr_t attr; > pthread_mutex_t lock; > struct timespec ts; > int error; > > (void)pthread_mutex_init(&lock, NULL); > > (void)pthread_condattr_init(&attr); > (void)pthread_condattr_setclock(&attr, CLOCK_MONOTONIC); > > (void)pthread_cond_init(&cv,&attr); > (void)pthread_condattr_destroy(&attr); > > (void)clock_gettime(CLOCK_MONOTONIC,&ts); > ts.tv_sec += 10; > (void)pthread_mutex_lock(&lock); > (void)pthread_cond_timedwait(&cv,&lock,&ts); > (void)pthread_mutex_unlock(&lock); > > This should timeout after 10 seconds, but pthread_cond_timedwait(3) > returns immediately with ETIMEDOUT. CLOCK_REALTIME works properly. > Bascially pthread_condattr_setclock(&attr, CLOCK_MONOTONIC) is no-op. > If you change CLOCK_MONOTONIC to CLOCK_REALTIME in clock_gettime(2) > call, it will timeout after 10 seconds. this has been broken for a while for me in fact fixing this was, I thought, one of the reasons for this work.. glad I'm not the omnly person seeing it though. for me it broke sysutils/fio from ports
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