AIX: Fix to get more accurate Thread's CPU time

src/base/platform/time.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/platform/time.h"
 
 #if V8_OS_POSIX
 #include <fcntl.h>  // for O_RDONLY
 #include <sys/time.h>
 #include <unistd.h>
@@ skipping 38 matching lines @@
   return absolute_micros.ValueOrDie();
 }
 #elif V8_OS_POSIX
 // Helper function to get results from clock_gettime() and convert to a
 // microsecond timebase. Minimum requirement is MONOTONIC_CLOCK to be supported
 // on the system. FreeBSD 6 has CLOCK_MONOTONIC but defines
 // _POSIX_MONOTONIC_CLOCK to -1.
 V8_INLINE int64_t ClockNow(clockid_t clk_id) {
 #if (defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0) || \
   defined(V8_OS_BSD) || defined(V8_OS_ANDROID)
+// On AIX clock_gettime for CLOCK_THREAD_CPUTIME_ID outputs time with
+// resolution of 10ms. thread_cputime API provides the time in ns
+#if defined(V8_OS_AIX)
+  thread_cputime_t tc;
+  if (clk_id == CLOCK_THREAD_CPUTIME_ID) {
+    if (thread_cputime(-1, &tc) != 0) {
+      UNREACHABLE();
+      return 0;
+    }
+  }
+#endif
   struct timespec ts;
   if (clock_gettime(clk_id, &ts) != 0) {
     UNREACHABLE();
     return 0;
   }
   v8::base::internal::CheckedNumeric<int64_t> result(ts.tv_sec);
   result *= v8::base::Time::kMicrosecondsPerSecond;
+#if defined(V8_OS_AIX)
+  if (clk_id == CLOCK_THREAD_CPUTIME_ID) {
+    result += (tc.stime / v8::base::Time::kNanosecondsPerMicrosecond);
+  } else {
+    result += (ts.tv_nsec / v8::base::Time::kNanosecondsPerMicrosecond);
+  }
+#else
   result += (ts.tv_nsec / v8::base::Time::kNanosecondsPerMicrosecond);
+#endif
   return result.ValueOrDie();
 #else  // Monotonic clock not supported.
   return 0;
 #endif
 }
 #elif V8_OS_WIN
 V8_INLINE bool IsQPCReliable() {
   v8::base::CPU cpu;
   // On Athlon X2 CPUs (e.g. model 15) QueryPerformanceCounter is unreliable.
   return strcmp(cpu.vendor(), "AuthenticAMD") == 0 && cpu.family() == 15;
@@ skipping 655 matching lines @@
   DCHECK_GE(tsc_now, tsc_initial);
   uint64_t tsc_ticks = tsc_now - tsc_initial;
   tsc_ticks_per_second = tsc_ticks / elapsed_time_seconds;
 
   return tsc_ticks_per_second;
 }
 #endif  // V8_OS_WIN
 
 }  // namespace base
 }  // namespace v8