Revision: 17642
Author: [email protected]
Date: Tue Nov 12 12:18:35 2013 UTC
Log: linux: use CLOCK_{REALTIME,MONOTONIC}_COARSE
[email protected]
Review URL: https://codereview.chromium.org/68203004
Patch from Ben Noordhuis <[email protected]>.
http://code.google.com/p/v8/source/detail?r=17642
Modified:
/branches/bleeding_edge/src/platform/time.cc
/branches/bleeding_edge/src/platform/time.h
=======================================
--- /branches/bleeding_edge/src/platform/time.cc Mon Nov 11 08:46:45 2013
UTC
+++ /branches/bleeding_edge/src/platform/time.cc Tue Nov 12 12:18:35 2013
UTC
@@ -43,6 +43,17 @@
#include "win32-headers.h"
#endif
+// Make sure CLOCK_{MONOTONIC,REALTIME}_COARSE is defined on Linux.
+#if V8_OS_LINUX
+# if !defined(CLOCK_REALTIME_COARSE)
+# define CLOCK_REALTIME_COARSE 5 // 2.6.32 and up.
+# endif
+# if !defined(CLOCK_MONOTONIC_COARSE)
+# define CLOCK_MONOTONIC_COARSE 6 // 2.6.32 and up.
+# endif
+#endif // V8_OS_LINUX
+
+
namespace v8 {
namespace internal {
@@ -271,11 +282,38 @@
#elif V8_OS_POSIX
Time Time::Now() {
+#if V8_LIBRT_NOT_AVAILABLE
+ // TODO(bmeurer): This is a temporary hack to support cross-compiling
+ // Chrome for Android in AOSP. Remove this once AOSP is fixed, also
+ // cleanup the tools/gyp/v8.gyp file.
struct timeval tv;
int result = gettimeofday(&tv, NULL);
ASSERT_EQ(0, result);
USE(result);
return FromTimeval(tv);
+#elif defined(CLOCK_REALTIME_COARSE)
+ struct timespec ts;
+ // Use CLOCK_REALTIME_COARSE if it's available and has a precision of 1ms
+ // or higher. It's serviced from the vDSO with no system call overhead.
+ static clock_t clock_id = static_cast<clock_t>(0);
+ if (!clock_id) {
+ if (clock_getres(CLOCK_REALTIME_COARSE, &ts) == 0
+ && ts.tv_nsec <= kNanosecondsPerMillisecond)
+ clock_id = CLOCK_REALTIME_COARSE;
+ else
+ clock_id = CLOCK_REALTIME;
+ }
+ int result = clock_gettime(clock_id, &ts);
+ ASSERT_EQ(0, result);
+ USE(result);
+ return FromTimespec(ts);
+#else
+ struct timeval tv;
+ int result = gettimeofday(&tv, NULL);
+ ASSERT_EQ(0, result);
+ USE(result);
+ return FromTimeval(tv);
+#endif // V8_LIBRT_NOT_AVAILABLE
}
@@ -570,7 +608,21 @@
ticks = (tv.tv_sec * Time::kMicrosecondsPerSecond + tv.tv_usec);
#elif V8_OS_POSIX
struct timespec ts;
- int result = clock_gettime(CLOCK_MONOTONIC, &ts);
+#if defined(CLOCK_MONOTONIC_COARSE)
+ // Use CLOCK_MONOTONIC_COARSE if it's available and has a precision of
1ms
+ // or higher. It's serviced from the vDSO with no system call overhead.
+ static clock_t clock_id = static_cast<clock_t>(0);
+ if (!clock_id) {
+ if (clock_getres(CLOCK_MONOTONIC_COARSE, &ts) == 0
+ && ts.tv_nsec <= Time::kNanosecondsPerMillisecond)
+ clock_id = CLOCK_MONOTONIC_COARSE;
+ else
+ clock_id = CLOCK_MONOTONIC;
+ }
+#else
+ static const clock_t clock_id = CLOCK_MONOTONIC;
+#endif // defined(CLOCK_MONOTONIC_COARSE)
+ int result = clock_gettime(clock_id, &ts);
ASSERT_EQ(0, result);
USE(result);
ticks = (ts.tv_sec * Time::kMicrosecondsPerSecond +
=======================================
--- /branches/bleeding_edge/src/platform/time.h Fri Oct 4 14:53:16 2013 UTC
+++ /branches/bleeding_edge/src/platform/time.h Tue Nov 12 12:18:35 2013 UTC
@@ -192,6 +192,8 @@
static const int64_t kMicrosecondsPerDay = kMicrosecondsPerHour * 24;
static const int64_t kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;
static const int64_t kNanosecondsPerMicrosecond = 1000;
+ static const int64_t kNanosecondsPerMillisecond =
kNanosecondsPerMicrosecond *
+
kMicrosecondsPerMillisecond;
static const int64_t kNanosecondsPerSecond = kNanosecondsPerMicrosecond *
kMicrosecondsPerSecond;
--
--
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