Date: Tue, 27 Jun 2006 13:51:43 -0400 From: John Baldwin <jhb@freebsd.org> To: kmacy@fsmware.com Cc: kris@freebsd.org, Perforce Change Reviews <perforce@freebsd.org>, Kip Macy <kmacy@freebsd.org> Subject: Re: PERFORCE change 100121 for review Message-ID: <200606271351.43665.jhb@freebsd.org> In-Reply-To: <b1fa29170606270931p6fbbbf98vcfcad8dc50987024@mail.gmail.com> References: <200606270742.k5R7gCfT001310@repoman.freebsd.org> <200606271127.13228.jhb@freebsd.org> <b1fa29170606270931p6fbbbf98vcfcad8dc50987024@mail.gmail.com>
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On Tuesday 27 June 2006 12:31, Kip Macy wrote: > Point me at your tree. I do :-). > > -Kip Heh. The tree is at //depot/user/jhb/lock/... I can also just generate a diff if you'd prefer. > On 6/27/06, John Baldwin <jhb@freebsd.org> wrote: > > On Tuesday 27 June 2006 03:42, Kip Macy wrote: > > > 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 > > > > Yes, I did this already in jhb_lock for both mutexes and rwlocks at BSDCan. > > Kris said my patch panic'd for him at BSDCan but I don't have an SMP machine > > I can test it on now to debug it. :( > > > > > > > > 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; > > > > > > > -- > > John Baldwin > > > -- John Baldwin
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