From: Vsevolod Stakhov <vsevolod@rambler-co.ru>
Date: Wed, 17 Jun 2009 16:31:42 +0000 (+0400)
Subject: * Improve locking by using asm 'pause' command
X-Git-Tag: 0.2.7~117
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=2a21701f6c0f80d2a56639e7e2c156ed7179f0dd;p=rspamd.git

* Improve locking by using asm 'pause' command
* Try to fix read locking in rwlock
---

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 754b2200a..676119827 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,6 +34,7 @@ OPTION(ENABLE_GPERF_TOOLS  "Enable google perftools [default: OFF]"
 INCLUDE(CheckIncludeFiles)
 INCLUDE(CheckFunctionExists)
 INCLUDE(CheckSymbolExists)
+INCLUDE(CheckCSourceCompiles)
 INCLUDE(CheckLibraryExists)
 INCLUDE(FindPkgConfig)
 
@@ -229,6 +230,12 @@ CHECK_SYMBOL_EXISTS(_SC_NPROCESSORS_ONLN unistd.h HAVE_SC_NPROCESSORS_ONLN)
 CHECK_SYMBOL_EXISTS(CLOCK_PROCESS_CPUTIME_ID time.h HAVE_CLOCK_PROCESS_CPUTIME_ID)
 CHECK_SYMBOL_EXISTS(CLOCK_VIRTUAL time.h HAVE_CLOCK_VIRTUAL)
 
+CHECK_C_SOURCE_COMPILES ("#include <sys/types.h>
+                          int main (int argc, char **argv) {
+						  	__asm __volatile(\"pause\");
+							return 0;
+						  }" HAVE_ASM_PAUSE)
+
 IF(NOT HAVE_COMPATIBLE_QUEUE_H)
 	INCLUDE_DIRECTORIES(compat)
 ENDIF(NOT HAVE_COMPATIBLE_QUEUE_H)
diff --git a/config.h.in b/config.h.in
index 61bbc6068..12593da61 100644
--- a/config.h.in
+++ b/config.h.in
@@ -103,6 +103,8 @@
 
 #cmakedefine WITH_GPERF_TOOLS    1
 
+#cmakedefine HAVE_ASM_PAUSE      1
+
 #define RVERSION          "${RSPAMD_VERSION}"
 #define RSPAMD_MASTER_SITE_URL "${RSPAMD_MASTER_SITE_URL}"
 
diff --git a/src/mem_pool.c b/src/mem_pool.c
index e034ea652..e8be6a95c 100644
--- a/src/mem_pool.c
+++ b/src/mem_pool.c
@@ -343,17 +343,17 @@ __mutex_spin (memory_pool_mutex_t *mutex)
 		/* Spin again */
 		g_atomic_int_set (&mutex->spin, MUTEX_SPIN_COUNT);
 	}
-#ifdef HAVE_NANOSLEEP
+#ifdef HAVE_ASM_PAUSE
+	__asm __volatile("pause");
+#elif defined(HAVE_SCHED_YIELD)
+	(void)sched_yield ();
+#elif defined(HAVE_NANOSLEEP)
 	struct timespec ts;
 	ts.tv_sec = 0;
 	ts.tv_nsec = MUTEX_SLEEP_TIME;
 	/* Spin */
 	while (nanosleep (&ts, &ts) == -1 && errno == EINTR);
-#endif
-#ifdef HAVE_SCHED_YIELD
-	(void)sched_yield ();
-#endif
-#if !defined(HAVE_NANOSLEEP) && !defined(HAVE_SCHED_YIELD)
+#else
 #	error No methods to spin are defined
 #endif
 	return 1;
@@ -552,7 +552,9 @@ memory_pool_wlock_rwlock (memory_pool_rwlock_t *lock)
 void 
 memory_pool_runlock_rwlock (memory_pool_rwlock_t *lock)
 {
-	memory_pool_unlock_mutex (lock->__r_lock);
+	if (g_atomic_int_get (&lock->__r_lock->lock)) {
+		(void)g_atomic_int_dec_and_test (&lock->__r_lock->lock);
+	}
 }
 
 void