Author: mjg
Date: Fri May 11 06:59:54 2018
New Revision: 333483
URL: https://svnweb.freebsd.org/changeset/base/333483
Log:
rmlock: partially depessimize lock/unlock fastpath
Previusly the slow path was folded in and partially jumped over in the
common case.
Modified:
head/sys/kern/kern_rmlock.c
Modified: head/sys/kern/kern_rmlock.c
==============================================================================
--- head/sys/kern/kern_rmlock.c Fri May 11 06:55:02 2018 (r333482)
+++ head/sys/kern/kern_rmlock.c Fri May 11 06:59:54 2018 (r333483)
@@ -344,7 +344,7 @@ rm_sysinit(void *arg)
rm_init_flags(args->ra_rm, args->ra_desc, args->ra_flags);
}
-static int
+static __noinline int
_rm_rlock_hard(struct rmlock *rm, struct rm_priotracker *tracker, int trylock)
{
struct pcpu *pc;
@@ -459,15 +459,15 @@ _rm_rlock(struct rmlock *rm, struct rm_priotracker *tr
* Fast path to combine two common conditions into a single
* conditional jump.
*/
- if (0 == (td->td_owepreempt |
- CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)))
+ if (__predict_true(0 == (td->td_owepreempt |
+ CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus))))
return (1);
/* We do not have a read token and need to acquire one. */
return _rm_rlock_hard(rm, tracker, trylock);
}
-static void
+static __noinline void
_rm_unlock_hard(struct thread *td,struct rm_priotracker *tracker)
{
@@ -518,7 +518,7 @@ _rm_runlock(struct rmlock *rm, struct rm_priotracker *
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
THREAD_SLEEPING_OK();
- if (0 == (td->td_owepreempt | tracker->rmp_flags))
+ if (__predict_true(0 == (td->td_owepreempt | tracker->rmp_flags)))
return;
_rm_unlock_hard(td, tracker);
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