Changeset 320e6b5eaa2ea265c86b12c93f0ec57dec270fd4

Timestamp:

01/03/07 21:16:49 (2 years ago)

Author:

Rémi Denis-Courmont <rem@videolan.org>

git-committer:

Rémi Denis-Courmont <rem@videolan.org> 1172780209 +0000

git-parent:

[c13d67b82c674fffe5d65656aff7484c227a74a1]

git-author:

Rémi Denis-Courmont <rem@videolan.org> 1172780209 +0000

Message:

Cache system clock in userland to save a few avoidable sleeps.
Also restore (albeit not hard-coded this time) the old Linux custom
of not waiting for a delay shorter than the scheduler precision

Files:

• src/misc/mtime.c (modified) (11 diffs)

src/misc/mtime.c

@@ -111 +111 @@
-}
-
+/**
+ * Return a value that is no bigger than the clock precision
+ * (possibly zero).
+ */
+static inline unsigned mprec( void )
+{
+#if defined (HAVE_CLOCK_NANOSLEEP)
+    struct timespec ts;
+    if( clock_getres( CLOCK_MONOTONIC, &ts ))
+        clock_getres( CLOCK_REALTIME, &ts );
+
+    return ts.tv_nsec / 1000;
+#endif
+    return 0;
+}
+
+static unsigned prec = 0;
+static volatile mtime_t cached_time = 0;
-
-/**
@@ -120 +138 @@
-mtime_t mdate( void )
-{
+    mtime_t res;
+
-#if defined (HAVE_CLOCK_NANOSLEEP)
-    struct timespec ts;
@@ -130 +150 @@
-        (void)clock_gettime( CLOCK_REALTIME, &ts );
-
-turn
+s =
-           + (mtime_t)(ts.tv_nsec / 1000);
-
-#elif defined( HAVE_KERNEL_OS_H )
-turn( real_time_clock_usecs() 
+s = real_time_clock_usecs(
-
-#elif defined( WIN32 ) || defined( UNDER_CE )
@@ -176 +196 @@
-        lldiv_t d = lldiv (counter.QuadPart, freq);
-
-
-
+
-    }
-    else
@@ -189 +208 @@
-        static mtime_t i_previous_time = I64C(-1);
-        static int i_wrap_counts = -1;
-        mtime_t usec_time;
-
-        if( i_wrap_counts == -1 )
@@ -200 +218 @@
-
-        EnterCriticalSection( &date_lock );
-usec_time
+res
-            (i_wrap_counts * I64C(0x100000000) + GetTickCount());
-usec_time
+res
-        {
-            /* Counter wrapped */
@@ -210 +228 @@
-        i_previous_time = usec_time;
-        LeaveCriticalSection( &date_lock );
-
-        return usec_time;
-    }
-#else
@@ -218 +234 @@
-    /* gettimeofday() cannot fail given &tv_date is a valid address */
-    (void)gettimeofday( &tv_date, NULL );
-
-
+
+
+
+
-}
-
@@ -232 +250 @@
-void mwait( mtime_t date )
-{
+    if( prec == 0 )
+        prec = mprec();
+
+    /* If the deadline is already elapsed, or within the clock precision,
+     * do not even bother the clock. */
+    if( ( date - cached_time ) < (mtime_t)prec ) // OK: mtime_t is signed
+        return;
+
-#if 0 && defined (HAVE_CLOCK_NANOSLEEP)
-    lldiv_t d = lldiv( date, 1000000 );
@@ -257 +283 @@
-void msleep( mtime_t delay )
-{
+    mtime_t earlier = cached_time;
+
-#if defined( HAVE_CLOCK_NANOSLEEP ) 
-    lldiv_t d = lldiv( delay, 1000000 );
@@ -298 +326 @@
-    select( 0, NULL, NULL, NULL, &tv_delay );
-#endif
+
+    earlier += delay;
+    if( cached_time < earlier )
+        cached_time = earlier;
-}
-