GNU C Library master sources branch master updated. glibc-2.22-539-g9695cb3

tuliom@sourceware.org tuliom@sourceware.org
Thu Nov 19 20:11:00 GMT 2015


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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=9695cb3e6528d9f6f5c7c7f96bd6c94e5ba0e2c4

commit 9695cb3e6528d9f6f5c7c7f96bd6c94e5ba0e2c4
Author: Paul Murphy <murphyp@linux.vnet.ibm.com>
Date:   Thu Oct 29 15:48:47 2015 -0500

    powerpc: Spinlock optimization and cleanup
    
    This patch optimizes powerpc spinlock implementation by:
    
    * Use the correct EH hint bit on the larx for supported ISA.  For lock
      acquisition, the thread that acquired the lock with a successful stcx
      does not want to give away the write ownership on the cacheline.  The
      idea is to make the load reservation "sticky" about retaining write
      authority to the line.  That way, the store that must inevitably come
      to release the lock can succeed quickly and not contend with other
      threads issuing lwarx.  If another thread does a store to the line
      (false sharing), the winning thread must give up write authority to
      the proper value of EH for the larx for a lock acquisition is 1.
    
    * Increase contented lock performance by up to 40%, and no measurable
      impact on uncontended locks on P8.
    
    Thanks to Adhemerval Zanella who did most of the work.  I've run some
    tests, and addressed some minor feedback.
    
    	* sysdeps/powerpc/nptl/pthread_spin_lock.c (pthread_spin_lock):
    	Add lwarx hint, and use macro for acquire instruction.
    	* sysdeps/powerpc/nptl/pthread_spin_trylock.c (pthread_spin_trylock):
    	Likewise.
    	* sysdep/unix/sysv/linux/powerpc/pthread_spin_unlock.c: Move to ...
    	* sysdeps/powerpc/nptl/pthread_spin_unlock.c: ... here, and
    	update to use new atomic macros.

diff --git a/ChangeLog b/ChangeLog
index a5440e2..d822095 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2015-11-19  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+	    Paul E. Murphy  <murphyp@linux.vnet.ibm.com>
+
+	* sysdeps/powerpc/nptl/pthread_spin_lock.c (pthread_spin_lock):
+	Add lwarx hint, and use macro for acquire instruction.
+	* sysdeps/powerpc/nptl/pthread_spin_trylock.c (pthread_spin_trylock):
+	Likewise.
+	* sysdep/unix/sysv/linux/powerpc/pthread_spin_unlock.c: Move to ...
+	* sysdeps/powerpc/nptl/pthread_spin_unlock.c: ... here, and
+	update to use new atomic macros.
+
 2015-11-19  Paul E. Murphy  <murphyp@linux.vnet.ibm.com>
 
 	* sysdeps/unix/sysv/linux/powerpc/elision-trylock.c
diff --git a/sysdeps/powerpc/nptl/pthread_spin_lock.c b/sysdeps/powerpc/nptl/pthread_spin_lock.c
index d7d4cae..fae7f7e 100644
--- a/sysdeps/powerpc/nptl/pthread_spin_lock.c
+++ b/sysdeps/powerpc/nptl/pthread_spin_lock.c
@@ -24,12 +24,12 @@ pthread_spin_lock (pthread_spinlock_t *lock)
   unsigned int __tmp;
 
   asm volatile (
-       "1:	lwarx	%0,0,%1\n"
+       "1:	lwarx	%0,0,%1" MUTEX_HINT_ACQ "\n"
        "	cmpwi	0,%0,0\n"
        "	bne-	2f\n"
        "	stwcx.	%2,0,%1\n"
        "	bne-	2f\n"
-       "	isync\n"
+                __ARCH_ACQ_INSTR "\n"
        "	.subsection 1\n"
        "2:	lwzx	%0,0,%1\n"
        "	cmpwi	0,%0,0\n"
diff --git a/sysdeps/powerpc/nptl/pthread_spin_trylock.c b/sysdeps/powerpc/nptl/pthread_spin_trylock.c
index c485aa4..09791c3 100644
--- a/sysdeps/powerpc/nptl/pthread_spin_trylock.c
+++ b/sysdeps/powerpc/nptl/pthread_spin_trylock.c
@@ -25,13 +25,13 @@ pthread_spin_trylock (pthread_spinlock_t *lock)
   unsigned int old;
   int err = EBUSY;
 
-  asm ("1:	lwarx	%0,0,%2\n"
+  asm ("1:	lwarx	%0,0,%2" MUTEX_HINT_ACQ "\n"
        "	cmpwi	0,%0,0\n"
        "	bne	2f\n"
        "	stwcx.	%3,0,%2\n"
        "	bne-	1b\n"
        "	li	%1,0\n"
-       "	isync\n"
+                __ARCH_ACQ_INSTR "\n"
        "2:	"
        : "=&r" (old), "=&r" (err)
        : "r" (lock), "r" (1), "1" (err)
diff --git a/sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c b/sysdeps/powerpc/nptl/pthread_spin_unlock.c
similarity index 93%
rename from sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c
rename to sysdeps/powerpc/nptl/pthread_spin_unlock.c
index 7af694f..f830ad2 100644
--- a/sysdeps/unix/sysv/linux/powerpc/pthread_spin_unlock.c
+++ b/sysdeps/powerpc/nptl/pthread_spin_unlock.c
@@ -22,7 +22,6 @@
 int
 pthread_spin_unlock (pthread_spinlock_t *lock)
 {
-  __asm __volatile (__ARCH_REL_INSTR ::: "memory");
-  *lock = 0;
+  atomic_store_release (lock, 0);
   return 0;
 }

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                          |   11 +++++++++++
 sysdeps/powerpc/nptl/pthread_spin_lock.c           |    4 ++--
 sysdeps/powerpc/nptl/pthread_spin_trylock.c        |    4 ++--
 .../powerpc => powerpc/nptl}/pthread_spin_unlock.c |    3 +--
 4 files changed, 16 insertions(+), 6 deletions(-)
 rename sysdeps/{unix/sysv/linux/powerpc => powerpc/nptl}/pthread_spin_unlock.c (93%)


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