Date: Tue, 27 Jun 2006 07:42:12 GMT From: Kip Macy <kmacy@FreeBSD.org> To: Perforce Change Reviews <perforce@freebsd.org> Subject: PERFORCE change 100121 for review Message-ID: <200606270742.k5R7gCfT001310@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=100121 Change 100121 by kmacy@kmacy_storage:sun4v_work_sleepq on 2006/06/27 07:41:14 avoid pointless turnstile contention if mutex owner is running Affected files ... .. //depot/projects/kmacy_sun4v/src/sys/kern/kern_mutex.c#20 edit Differences ... ==== //depot/projects/kmacy_sun4v/src/sys/kern/kern_mutex.c#20 (text+ko) ==== @@ -176,7 +176,7 @@ static int mutex_prof_maxrecords = MPROF_HASH_SIZE; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD, &mutex_prof_maxrecords, 0, "Maximum number of profiling records"); -int mutex_prof_rejected; +int mutex_prof_rejected = 0; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD, &mutex_prof_rejected, 0, "Number of rejected profiling records"); static int mutex_prof_hashsize = MPROF_HASH_SIZE; @@ -418,6 +418,16 @@ while (!_obtain_lock(m, tid)) { lock_profile_obtain_lock_failed(&m->mtx_object, &contested); +#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) + /* + * If the current owner of the lock is executing on another + * CPU, spin instead of blocking. + */ + for (owner = mtx_owner(m); owner && TD_IS_RUNNING(owner); owner = mtx_owner(m)) + cpu_spinwait(); + if (mtx_unowned(m)) + continue; +#endif /* SMP && !NO_ADAPTIVE_MUTEXES */ turnstile_lock(&m->mtx_object); v = m->mtx_lock; @@ -425,7 +435,7 @@ * Check if the lock has been released while spinning for * the turnstile chain lock. */ - if (v == MTX_UNOWNED) { + if (mtx_unowned(m)) { turnstile_release(&m->mtx_object); cpu_spinwait(); continue; @@ -837,6 +847,8 @@ mtx_validate(m); #endif + + /* Determine lock class and lock flags. */ if (opts & MTX_SPIN) class = &lock_class_mtx_spin;
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