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authorXavier Leroy <xavier.leroy@inria.fr>2007-10-31 09:12:29 +0000
committerXavier Leroy <xavier.leroy@inria.fr>2007-10-31 09:12:29 +0000
commit45f7137dd31ae5891ef6f9520fd174a04dc6c2a5 (patch)
tree5030fe4abe6afb89e12605412bc96751370e8af3 /otherlibs
parentbbc18ec5c086f2de97eb8e9d5d4aed35ce0832d5 (diff)
PR#4351: try to avoid rescheduling in mutex and condvar operations
git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@8468 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Diffstat (limited to 'otherlibs')
-rw-r--r--otherlibs/systhreads/posix.c57
-rw-r--r--otherlibs/systhreads/win32.c31
2 files changed, 32 insertions, 56 deletions
diff --git a/otherlibs/systhreads/posix.c b/otherlibs/systhreads/posix.c
index 679fb09b4..0e5354241 100644
--- a/otherlibs/systhreads/posix.c
+++ b/otherlibs/systhreads/posix.c
@@ -122,15 +122,11 @@ static pthread_key_t last_channel_locked_key;
/* Identifier for next thread creation */
static intnat thread_next_ident = 0;
-/* Whether to use sched_yield() or not */
-static int broken_sched_yield = 0;
-
/* Forward declarations */
value caml_threadstatus_new (void);
void caml_threadstatus_terminate (value);
int caml_threadstatus_wait (value);
static void caml_pthread_check (int, char *);
-static void caml_thread_sysdeps_initialize(void);
/* Imports for the native-code compiler */
extern struct longjmp_buffer caml_termination_jmpbuf;
@@ -258,6 +254,12 @@ static void caml_io_mutex_lock(struct channel *chan)
pthread_mutex_init(mutex, NULL);
chan->mutex = (void *) mutex;
}
+ /* PR#4351: first try to acquire mutex without releasing the master lock */
+ if (pthread_mutex_trylock(chan->mutex) == 0) {
+ pthread_setspecific(last_channel_locked_key, (void *) chan);
+ return;
+ }
+ /* If unsuccessful, block on mutex */
enter_blocking_section();
pthread_mutex_lock(chan->mutex);
/* Problem: if a signal occurs at this point,
@@ -338,8 +340,6 @@ value caml_thread_initialize(value unit) /* ML */
/* Protect against repeated initialization (PR#1325) */
if (curr_thread != NULL) return Val_unit;
Begin_root (mu);
- /* OS-specific initialization */
- caml_thread_sysdeps_initialize();
/* Initialize the keys */
pthread_key_create(&thread_descriptor_key, NULL);
pthread_key_create(&last_channel_locked_key, NULL);
@@ -562,7 +562,10 @@ value caml_thread_yield(value unit) /* ML */
{
if (caml_runtime_waiters == 0) return Val_unit;
enter_blocking_section();
- if (! broken_sched_yield) sched_yield();
+#ifndef __linux__
+ /* sched_yield() doesn't do what we want in Linux 2.6 and up (PR#2663) */
+ sched_yield();
+#endif
leave_blocking_section();
return Val_unit;
}
@@ -620,6 +623,10 @@ value caml_mutex_lock(value wrapper) /* ML */
{
int retcode;
pthread_mutex_t * mut = Mutex_val(wrapper);
+ /* PR#4351: first try to acquire mutex without releasing the master lock */
+ retcode = pthread_mutex_trylock(mut);
+ if (retcode == 0) return Val_unit;
+ /* If unsuccessful, block on mutex */
Begin_root(wrapper) /* prevent the deallocation of mutex */
enter_blocking_section();
retcode = pthread_mutex_lock(mut);
@@ -633,11 +640,8 @@ value caml_mutex_unlock(value wrapper) /* ML */
{
int retcode;
pthread_mutex_t * mut = Mutex_val(wrapper);
- Begin_root(wrapper) /* prevent the deallocation of mutex */
- enter_blocking_section();
- retcode = pthread_mutex_unlock(mut);
- leave_blocking_section();
- End_roots();
+ /* PR#4351: no need to release and reacquire master lock */
+ retcode = pthread_mutex_unlock(mut);
caml_pthread_check(retcode, "Mutex.unlock");
return Val_unit;
}
@@ -703,11 +707,7 @@ value caml_condition_signal(value wrapper) /* ML */
{
int retcode;
pthread_cond_t * cond = Condition_val(wrapper);
- Begin_root(wrapper) /* prevent deallocation of condition */
- enter_blocking_section();
- retcode = pthread_cond_signal(cond);
- leave_blocking_section();
- End_roots();
+ retcode = pthread_cond_signal(cond);
caml_pthread_check(retcode, "Condition.signal");
return Val_unit;
}
@@ -716,11 +716,7 @@ value caml_condition_broadcast(value wrapper) /* ML */
{
int retcode;
pthread_cond_t * cond = Condition_val(wrapper);
- Begin_root(wrapper) /* prevent deallocation of condition */
- enter_blocking_section();
- retcode = pthread_cond_broadcast(cond);
- leave_blocking_section();
- End_roots();
+ retcode = pthread_cond_broadcast(cond);
caml_pthread_check(retcode, "Condition.broadcast");
return Val_unit;
}
@@ -888,20 +884,3 @@ static void caml_pthread_check(int retcode, char *msg)
raise_sys_error(str);
}
-/* OS-specific initialization */
-
-static void caml_thread_sysdeps_initialize(void)
-{
-#ifdef __linux__
- /* sched_yield() doesn't do what we want in kernel 2.6 and up (PR#2663) */
- struct utsname un;
- if (uname(&un) == -1) return;
- broken_sched_yield =
- un.release[1] != '.' || un.release[0] >= '3' /* version 3 and up */
- || (un.release[0] == '2' &&
- (un.release[3] != '.' || un.release[2] >= '6')); /* 2.6 and up */
- caml_gc_message(0x100, "POSIX threads. Avoid sched_yield: %d\n",
- broken_sched_yield);
-#endif
-}
-
diff --git a/otherlibs/systhreads/win32.c b/otherlibs/systhreads/win32.c
index b505a0f98..dfec43ccb 100644
--- a/otherlibs/systhreads/win32.c
+++ b/otherlibs/systhreads/win32.c
@@ -227,6 +227,11 @@ static void caml_io_mutex_lock(struct channel * chan)
if (mutex == NULL) caml_wthread_error("Thread.iolock");
chan->mutex = (void *) mutex;
}
+ /* PR#4351: first try to acquire mutex without releasing the master lock */
+ if (WaitForSingleObject((HANDLE) chan->mutex, 0) == WAIT_OBJECT_0) {
+ TlsSetValue(last_channel_locked_key, (void *) chan);
+ return;
+ }
enter_blocking_section();
WaitForSingleObject((HANDLE) chan->mutex, INFINITE);
/* Problem: if a signal occurs at this point,
@@ -518,6 +523,9 @@ CAMLprim value caml_mutex_new(value unit)
CAMLprim value caml_mutex_lock(value mut)
{
int retcode;
+ /* PR#4351: first try to acquire mutex without releasing the master lock */
+ retcode = WaitForSingleObject(Mutex_val(mut), 0);
+ if (retcode == WAIT_OBJECT_0) return Val_unit;
Begin_root(mut) /* prevent deallocation of mutex */
enter_blocking_section();
retcode = WaitForSingleObject(Mutex_val(mut), INFINITE);
@@ -530,11 +538,8 @@ CAMLprim value caml_mutex_lock(value mut)
CAMLprim value caml_mutex_unlock(value mut)
{
BOOL retcode;
- Begin_root(mut) /* prevent deallocation of mutex */
- enter_blocking_section();
- retcode = ReleaseMutex(Mutex_val(mut));
- leave_blocking_section();
- End_roots();
+ /* PR#4351: no need to release and reacquire master lock */
+ retcode = ReleaseMutex(Mutex_val(mut));
if (!retcode) caml_wthread_error("Mutex.unlock");
return Val_unit;
}
@@ -630,12 +635,8 @@ CAMLprim value caml_condition_signal(value cond)
if (Condition_val(cond)->count > 0) {
Condition_val(cond)->count --;
- Begin_root(cond) /* prevent deallocation of cond */
- enter_blocking_section();
- /* Increment semaphore by 1, waking up one waiter */
- ReleaseSemaphore(s, 1, NULL);
- leave_blocking_section();
- End_roots();
+ /* Increment semaphore by 1, waking up one waiter */
+ ReleaseSemaphore(s, 1, NULL);
}
return Val_unit;
}
@@ -647,12 +648,8 @@ CAMLprim value caml_condition_broadcast(value cond)
if (c > 0) {
Condition_val(cond)->count = 0;
- Begin_root(cond) /* prevent deallocation of cond */
- enter_blocking_section();
- /* Increment semaphore by c, waking up all waiters */
- ReleaseSemaphore(s, c, NULL);
- leave_blocking_section();
- End_roots();
+ /* Increment semaphore by c, waking up all waiters */
+ ReleaseSemaphore(s, c, NULL);
}
return Val_unit;
}
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