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Date:      Fri, 29 May 2009 14:03:34 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r193037 - head/sys/kern
Message-ID:  <200905291403.n4TE3YiR076840@svn.freebsd.org>
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Author: jhb
Date: Fri May 29 14:03:34 2009
New Revision: 193037
URL: http://svn.freebsd.org/changeset/base/193037

Log:
  Remove extra cpu_spinwait() invocations.  This should really only be used
  in tight spin loops, not in these edge cases where we restart a much
  larger loop only a few times.
  
  Reviewed by:	attilio

Modified:
  head/sys/kern/kern_mutex.c
  head/sys/kern/kern_rwlock.c

Modified: head/sys/kern/kern_mutex.c
==============================================================================
--- head/sys/kern/kern_mutex.c	Fri May 29 14:02:45 2009	(r193036)
+++ head/sys/kern/kern_mutex.c	Fri May 29 14:03:34 2009	(r193037)
@@ -393,7 +393,6 @@ _mtx_lock_sleep(struct mtx *m, uintptr_t
 		 */
 		if (v == MTX_UNOWNED) {
 			turnstile_cancel(ts);
-			cpu_spinwait();
 			continue;
 		}
 
@@ -408,7 +407,6 @@ _mtx_lock_sleep(struct mtx *m, uintptr_t
 		owner = (struct thread *)(v & ~MTX_FLAGMASK);
 		if (TD_IS_RUNNING(owner)) {
 			turnstile_cancel(ts);
-			cpu_spinwait();
 			continue;
 		}
 #endif
@@ -421,7 +419,6 @@ _mtx_lock_sleep(struct mtx *m, uintptr_t
 		if ((v & MTX_CONTESTED) == 0 &&
 		    !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
 			turnstile_cancel(ts);
-			cpu_spinwait();
 			continue;
 		}
 

Modified: head/sys/kern/kern_rwlock.c
==============================================================================
--- head/sys/kern/kern_rwlock.c	Fri May 29 14:02:45 2009	(r193036)
+++ head/sys/kern/kern_rwlock.c	Fri May 29 14:03:34 2009	(r193037)
@@ -350,7 +350,6 @@ _rw_rlock(struct rwlock *rw, const char 
 					    (void *)(v + RW_ONE_READER));
 				break;
 			}
-			cpu_spinwait();
 			continue;
 		}
 		lock_profile_obtain_lock_failed(&rw->lock_object,
@@ -406,7 +405,6 @@ _rw_rlock(struct rwlock *rw, const char 
 		v = rw->rw_lock;
 		if (RW_CAN_READ(v)) {
 			turnstile_cancel(ts);
-			cpu_spinwait();
 			continue;
 		}
 
@@ -422,7 +420,6 @@ _rw_rlock(struct rwlock *rw, const char 
 			owner = (struct thread *)RW_OWNER(v);
 			if (TD_IS_RUNNING(owner)) {
 				turnstile_cancel(ts);
-				cpu_spinwait();
 				continue;
 			}
 		}
@@ -443,7 +440,6 @@ _rw_rlock(struct rwlock *rw, const char 
 			if (!atomic_cmpset_ptr(&rw->rw_lock, v,
 			    v | RW_LOCK_READ_WAITERS)) {
 				turnstile_cancel(ts);
-				cpu_spinwait();
 				continue;
 			}
 			if (LOCK_LOG_TEST(&rw->lock_object, 0))
@@ -695,7 +691,6 @@ _rw_wlock_hard(struct rwlock *rw, uintpt
 			if (!(v & RW_LOCK_WRITE_SPINNER)) {
 				if (!atomic_cmpset_ptr(&rw->rw_lock, v,
 				    v | RW_LOCK_WRITE_SPINNER)) {
-					cpu_spinwait();
 					continue;
 				}
 			}
@@ -727,7 +722,6 @@ _rw_wlock_hard(struct rwlock *rw, uintpt
 			owner = (struct thread *)RW_OWNER(v);
 			if (TD_IS_RUNNING(owner)) {
 				turnstile_cancel(ts);
-				cpu_spinwait();
 				continue;
 			}
 		}
@@ -750,7 +744,6 @@ _rw_wlock_hard(struct rwlock *rw, uintpt
 				break;
 			}
 			turnstile_cancel(ts);
-			cpu_spinwait();
 			continue;
 		}
 		/*
@@ -762,7 +755,6 @@ _rw_wlock_hard(struct rwlock *rw, uintpt
 			if (!atomic_cmpset_ptr(&rw->rw_lock, v,
 			    v | RW_LOCK_WRITE_WAITERS)) {
 				turnstile_cancel(ts);
-				cpu_spinwait();
 				continue;
 			}
 			if (LOCK_LOG_TEST(&rw->lock_object, 0))

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