Revision: 17611
Author: [email protected]
Date: Mon Nov 11 07:49:18 2013 UTC
Log: Use CLOCK_MONOTONIC_COARSE and CLOCK_REALTIME_COARSE on Linux if
available.
[email protected]
Review URL: https://codereview.chromium.org/51333007
Patch from Ben Noordhuis <[email protected]>.
http://code.google.com/p/v8/source/detail?r=17611
Modified:
/branches/bleeding_edge/src/platform/time.cc
=======================================
--- /branches/bleeding_edge/src/platform/time.cc Wed Oct 2 13:30:31 2013
UTC
+++ /branches/bleeding_edge/src/platform/time.cc Mon Nov 11 07:49:18 2013
UTC
@@ -43,6 +43,15 @@
#include "win32-headers.h"
#endif
+#if V8_OS_LINUX
+#if !defined(CLOCK_REALTIME_COARSE)
+#define CLOCK_REALTIME_COARSE 5 // 2.6.32 and up.
+#endif // !defined(CLOCK_REALTIME_COARSE)
+#if !defined(CLOCK_MONOTONIC_COARSE)
+#define CLOCK_MONOTONIC_COARSE 6 // 2.6.32 and up.
+#endif // !defined(CLOCK_MONOTONIC_COARSE)
+#endif // V8_OS_LINUX
+
namespace v8 {
namespace internal {
@@ -271,11 +280,29 @@
#elif V8_OS_POSIX
Time Time::Now() {
+#if V8_OS_LINUX
+ // Use CLOCK_REALTIME_COARSE if it's available and has a precision of 1
ms
+ // or higher. It's serviced from the vDSO with no system call overhead.
+ static clock_t clock_id = -1;
+ struct timespec ts;
+ if (clock_id == -1) {
+ if (clock_getres(CLOCK_REALTIME_COARSE, &ts) || ts.tv_nsec > 1000 *
1000) {
+ clock_id = CLOCK_REALTIME;
+ } else {
+ clock_id = CLOCK_REALTIME_COARSE;
+ }
+ }
+ int result = clock_gettime(clock_id, &ts);
+ ASSERT_EQ(0, result);
+ USE(result);
+ return FromTimespec(ts);
+#else // V8_OS_LINUX
struct timeval tv;
int result = gettimeofday(&tv, NULL);
ASSERT_EQ(0, result);
USE(result);
return FromTimeval(tv);
+#endif // V8_OS_LINUX
}
@@ -570,7 +597,21 @@
ticks = (tv.tv_sec * Time::kMicrosecondsPerSecond + tv.tv_usec);
#elif V8_OS_POSIX
struct timespec ts;
+#if V8_OS_LINUX
+ // Use CLOCK_MONOTONIC_COARSE if it's available and has a precision of 1
ms
+ // or higher. It's serviced from the vDSO with no system call overhead.
+ static clock_t clock_id = -1;
+ if (clock_id == -1) {
+ if (clock_getres(CLOCK_MONOTONIC_COARSE, &ts) || ts.tv_nsec > 1000 *
1000) {
+ clock_id = CLOCK_MONOTONIC;
+ } else {
+ clock_id = CLOCK_MONOTONIC_COARSE;
+ }
+ }
+ int result = clock_gettime(clock_id, &ts);
+#else
int result = clock_gettime(CLOCK_MONOTONIC, &ts);
+#endif // V8_OS_LINUX
ASSERT_EQ(0, result);
USE(result);
ticks = (ts.tv_sec * Time::kMicrosecondsPerSecond +
--
--
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