Update.

2001-08-29  Ulrich Drepper  <drepper@redhat.com>

	* spinlock.c (__pthread_lock): Top max_count value with
	MAX_ADAPTIVE_SPIN_COUNT.
	* internals.h (MAX_ADAPTIVE_SPIN_COUNT): Define if not already done.

	* sysdeps/i386/i686/pt-machine.h (BUSY_WAIT_NOP): New macro to
	help P4.

diff --git a/linuxthreads/ChangeLog b/linuxthreads/ChangeLog
index 1ce5a23..b85f8c9 100644 (file)
--- a/linuxthreads/ChangeLog
+++ b/linuxthreads/ChangeLog
@@ -1,3 +1,12 @@
+2001-08-29  Ulrich Drepper  <drepper@redhat.com>
+
+       * spinlock.c (__pthread_lock): Top max_count value with
+       MAX_ADAPTIVE_SPIN_COUNT.
+       * internals.h (MAX_ADAPTIVE_SPIN_COUNT): Define if not already done.
+
+       * sysdeps/i386/i686/pt-machine.h (BUSY_WAIT_NOP): New macro to
+       help P4.
+
 2001-08-27  Jakub Jelinek  <jakub@redhat.com>
 
        * sysdeps/pthread/bits/libc-lock.h (__libc_rwlock_t): Only define to

diff --git a/linuxthreads/internals.h b/linuxthreads/internals.h
index d5b469b..ae49266 100644 (file)
--- a/linuxthreads/internals.h
+++ b/linuxthreads/internals.h
@@ -414,6 +414,13 @@ static inline pthread_descr thread_self (void)
 #define MAX_SPIN_COUNT 50
 #endif
 
+/* Max number of times the spinlock in the adaptive mutex implementation
+   spins actively on SMP systems.  */
+
+#ifndef MAX_ADAPTIVE_SPIN_COUNT
+#define MAX_ADAPTIVE_SPIN_COUNT 100
+#endif
+
 /* Duration of sleep (in nanoseconds) when we can't acquire a spinlock
    after MAX_SPIN_COUNT iterations of sched_yield().
    With the 2.0 and 2.1 kernels, this MUST BE > 2ms.

diff --git a/linuxthreads/spinlock.c b/linuxthreads/spinlock.c
index 199386a..3e16825 100644 (file)
--- a/linuxthreads/spinlock.c
+++ b/linuxthreads/spinlock.c
@@ -94,6 +94,9 @@ again:
   if (__pthread_smp_kernel) {
     int max_count = lock->__spinlock * 2 + 10;
 
+    if (max_count > MAX_ADAPTIVE_SPIN_COUNT)
+      max_count = MAX_ADAPTIVE_SPIN_COUNT;
+
     for (spin_count = 0; spin_count < max_count; spin_count++) {
       if (((oldstatus = lock->__status) & 1) == 0) {
        if(__compare_and_swap(&lock->__status, oldstatus, oldstatus | 1))
@@ -104,6 +107,9 @@ again:
          return;
        }
       }
+#ifdef BUSY_WAIT_NOP
+      BUSY_WAIT_NOP;
+#endif
       __asm __volatile ("" : "=m" (lock->__status) : "0" (lock->__status));
     }
 

diff --git a/linuxthreads/sysdeps/i386/i686/pt-machine.h b/linuxthreads/sysdeps/i386/i686/pt-machine.h
index 7df3e7e..c739602 100644 (file)
--- a/linuxthreads/sysdeps/i386/i686/pt-machine.h
+++ b/linuxthreads/sysdeps/i386/i686/pt-machine.h
@@ -64,3 +64,6 @@ __compare_and_swap (long int *p, long int oldval, long int newval)
 #if __ASSUME_LDT_WORKS > 0
 #include "../useldt.h"
 #endif
+
+/* The P4 and above really want some help to prevent overheating.  */
+#define BUSY_WAIT_NOP  __asm__ ("rep; nop")