PERFORCE change 100121 for review
John Baldwin
jhb at freebsd.org
Tue Jun 27 18:36:00 UTC 2006
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 at 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 at 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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