Make recursive mutexes slightly faster

jart · Dec 30, 2024 · c7e3d9f · c7e3d9f
1 parent 9ba5b22
commit c7e3d9f
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Showing 6 changed files with 12 additions and 8 deletions.
diff --git a/libc/intrin/cosmo_futex.c b/libc/intrin/cosmo_futex.c
@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/atomic.h"
+#include "libc/calls/cp.internal.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/sig.internal.h"
 #include "libc/calls/struct/sigset.h"
@@ -232,6 +233,7 @@ static int cosmo_futex_fix_timeout (struct timespec *memory, int clock,
  * @raise EAGAIN if `*w` wasn't `expect`
  * @raise EINTR if a signal handler was called while waiting
  * @raise ECANCELED if calling thread was canceled while waiting
+ * @cancelationpoint
  */
 int cosmo_futex_wait (atomic_int *w, int expect, char pshare,
 		      int clock, const struct timespec *abstime) {
@@ -240,6 +242,7 @@ int cosmo_futex_wait (atomic_int *w, int expect, char pshare,
 	struct PosixThread *pt;
 	struct timespec tsmem;
 	struct timespec *timeout = 0;
+	BEGIN_CANCELATION_POINT;
 
 	cosmo_once (&g_cosmo_futex.once, cosmo_futex_init);
 
@@ -351,6 +354,7 @@ int cosmo_futex_wait (atomic_int *w, int expect, char pshare,
 		DescribeTimespec (0, abstime),
 		DescribeErrno (rc));
 
+	END_CANCELATION_POINT;
 	return rc;
 }
 

diff --git a/libc/intrin/gettid.c b/libc/intrin/gettid.c
@@ -39,7 +39,7 @@
 int gettid(void) {
   int tid;
   if (VERY_LIKELY(__tls_enabled && !__vforked)) {
-    tid = atomic_load_explicit(&__get_tls()->tib_tid, memory_order_acquire);
+    tid = atomic_load_explicit(&__get_tls()->tib_tid, memory_order_relaxed);
     if (VERY_LIKELY(tid > 0))
       return tid;
   }

diff --git a/libc/intrin/maps.c b/libc/intrin/maps.c
@@ -192,7 +192,7 @@ ABI void __maps_unlock(void) {
     return;
   if (tib->tib_flags & TIB_FLAG_VFORKED)
     return;
-  me = atomic_load_explicit(&tib->tib_tid, memory_order_acquire);
+  me = atomic_load_explicit(&tib->tib_tid, memory_order_relaxed);
   if (me <= 0)
     return;
   word = atomic_load_explicit(&__maps.lock.word, memory_order_relaxed);

diff --git a/libc/intrin/pthread_mutex_lock.c b/libc/intrin/pthread_mutex_lock.c
@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/blockcancel.internal.h"
-#include "libc/calls/calls.h"
 #include "libc/calls/state.internal.h"
 #include "libc/cosmo.h"
 #include "libc/dce.h"
@@ -70,7 +69,7 @@ static errno_t pthread_mutex_lock_recursive(pthread_mutex_t *mutex,
                                             uint64_t word, bool is_trylock) {
   uint64_t lock;
   int backoff = 0;
-  int me = gettid();
+  int me = atomic_load_explicit(&__get_tls()->tib_tid, memory_order_relaxed);
   bool once = false;
   for (;;) {
     if (MUTEX_OWNER(word) == me) {
@@ -120,7 +119,7 @@ static errno_t pthread_mutex_lock_recursive(pthread_mutex_t *mutex,
 static errno_t pthread_mutex_lock_recursive_nsync(pthread_mutex_t *mutex,
                                                   uint64_t word,
                                                   bool is_trylock) {
-  int me = gettid();
+  int me = atomic_load_explicit(&__get_tls()->tib_tid, memory_order_relaxed);
   for (;;) {
     if (MUTEX_OWNER(word) == me) {
       if (MUTEX_DEPTH(word) < MUTEX_DEPTH_MAX) {

diff --git a/libc/intrin/pthread_mutex_unlock.c b/libc/intrin/pthread_mutex_unlock.c
@@ -30,6 +30,7 @@
 #include "libc/thread/lock.h"
 #include "libc/thread/posixthread.internal.h"
 #include "libc/thread/thread.h"
+#include "libc/thread/tls.h"
 #include "third_party/nsync/mu.h"
 
 // see "take 3" algorithm in "futexes are tricky" by ulrich drepper
@@ -43,7 +44,7 @@ static void pthread_mutex_unlock_drepper(atomic_int *futex, char pshare) {
 
 static errno_t pthread_mutex_unlock_recursive(pthread_mutex_t *mutex,
                                               uint64_t word) {
-  int me = gettid();
+  int me = atomic_load_explicit(&__get_tls()->tib_tid, memory_order_relaxed);
   for (;;) {
 
     // we allow unlocking an initialized lock that wasn't locked, but we
@@ -75,7 +76,7 @@ static errno_t pthread_mutex_unlock_recursive(pthread_mutex_t *mutex,
 #if PTHREAD_USE_NSYNC
 static errno_t pthread_mutex_unlock_recursive_nsync(pthread_mutex_t *mutex,
                                                     uint64_t word) {
-  int me = gettid();
+  int me = atomic_load_explicit(&__get_tls()->tib_tid, memory_order_relaxed);
   for (;;) {
 
     // we allow unlocking an initialized lock that wasn't locked, but we

diff --git a/libc/intrin/pthread_setcancelstate.c b/libc/intrin/pthread_setcancelstate.c
@@ -81,7 +81,7 @@ errno_t pthread_setcancelstate(int state, int *oldstate) {
     }
     err = 0;
   }
-#if IsModeDbg()
+#if IsModeDbg() && 0
   STRACE("pthread_setcancelstate(%s, [%s]) → %s",
          DescribeCancelState(0, &state), DescribeCancelState(err, oldstate),
          DescribeErrno(err));