Merge pull request open-mpi#2611 from hjelmn/v2.0.x_timer

opal/timer: add code to check if rtdtsc is core invariant
jsquyres · Dec 20, 2016 · b393c3b · b393c3b
2 parents a5ab6eb + 7d3b07d
commit b393c3b
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Showing 3 changed files with 47 additions and 17 deletions.
diff --git a/opal/include/opal/sys/amd64/timer.h b/opal/include/opal/sys/amd64/timer.h
@@ -1,3 +1,4 @@
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
 /*
  * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
@@ -9,6 +10,8 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2016      Los Alamos National Security, LLC. ALl rights
+ *                         reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -56,7 +59,24 @@ opal_sys_timer_get_cycles(void)
      return ((opal_timer_t)l) | (((opal_timer_t)h) << 32);
 }
 
+static inline bool opal_sys_timer_is_monotonic (void)
+{
+    int32_t cpuid1, cpuid2, tmp;
+    const int32_t level = 0x80000007;
+    /* cpuid clobbers ebx but it must be restored for -fPIC so save
+     * then restore ebx */
+    __asm__ volatile ("xchgl %%ebx, %2\n"
+                      "cpuid\n"
+                      "xchgl %%ebx, %2\n":
+                      "=a" (cpuid1), "=d" (cpuid2), "=r" (tmp) :
+                      "a" (level) :
+                      "ecx");
+    /* bit 8 of edx contains the invariant tsc flag */
+    return !!(cpuid2 & (1 << 8));
+}
+
 #define OPAL_HAVE_SYS_TIMER_GET_CYCLES 1
+#define OPAL_HAVE_SYS_TIMER_IS_MONOTONIC 1
 
 #else
 

diff --git a/opal/include/opal/sys/timer.h b/opal/include/opal/sys/timer.h
@@ -1,3 +1,4 @@
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
 /*
  * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
@@ -9,6 +10,8 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2016      Los Alamos National Security, LLC. All rights
+ *                         reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -108,6 +111,17 @@ typedef long opal_timer_t;
 #endif
 #endif
 
+#ifndef OPAL_HAVE_SYS_TIMER_IS_MONOTONIC
+
+#define OPAL_HAVE_SYS_TIMER_IS_MONOTONIC 1
+
+static inline bool opal_sys_timer_is_monotonic (void)
+{
+    return OPAL_TIMER_MONOTONIC;
+}
+
+#endif
+
 END_C_DECLS
 
 #endif /* OPAL_SYS_TIMER_H */
diff --git a/opal/mca/timer/linux/timer_linux_component.c b/opal/mca/timer/linux/timer_linux_component.c
@@ -12,7 +12,7 @@
  *                         All rights reserved.
  * Copyright (c) 2015      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
- * Copyright (c) 2015      Los Alamos National Security, LLC. All rights
+ * Copyright (c) 2015-2016 Los Alamos National Security, LLC. All rights
  *                         reserved.
  * Copyright (c) 2015 Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
@@ -153,8 +153,8 @@ int opal_timer_linux_open(void)
 {
     int ret = OPAL_SUCCESS;
 
-    if(mca_timer_base_monotonic) {
-#if OPAL_HAVE_CLOCK_GETTIME
+    if (mca_timer_base_monotonic && !opal_sys_timer_is_monotonic ()) {
+#if OPAL_HAVE_CLOCK_GETTIME && (0 == OPAL_TIMER_MONOTONIC)
         struct timespec res;
         if( 0 == clock_getres(CLOCK_MONOTONIC, &res)) {
             opal_timer_linux_freq = 1.e9;
@@ -163,11 +163,9 @@ int opal_timer_linux_open(void)
             return ret;
         }
 #else
-#if (0 == OPAL_TIMER_MONOTONIC)
         /* Monotonic time requested but cannot be found. Complain! */
-        opal_show_help("help-opal-timer-linux.txt", "monotonic not supported", 1);
-#endif  /* (0 == OPAL_TIMER_MONOTONIC) */
-#endif
+        opal_show_help("help-opal-timer-linux.txt", "monotonic not supported", true);
+#endif  /* OPAL_HAVE_CLOCK_GETTIME && (0 == OPAL_TIMER_MONOTONIC) */
     }
     ret = opal_timer_linux_find_freq();
     opal_timer_base_get_cycles = opal_timer_base_get_cycles_sys_timer;
@@ -178,22 +176,20 @@ int opal_timer_linux_open(void)
 #if OPAL_HAVE_CLOCK_GETTIME
 opal_timer_t opal_timer_base_get_usec_clock_gettime(void)
 {
-    struct timespec tp;
+    struct timespec tp = {.tv_sec = 0, .tv_nsec = 0};
 
-    if( 0 == clock_gettime(CLOCK_MONOTONIC, &tp) ) {
-        return (tp.tv_sec * 1e6 + tp.tv_nsec/1000);
-    }
-    return 0;
+    (void) clock_gettime (CLOCK_MONOTONIC, &tp);
+
+    return (tp.tv_sec * 1e6 + tp.tv_nsec/1000);
 }
 
 opal_timer_t opal_timer_base_get_cycles_clock_gettime(void)
 {
-    struct timespec tp;
+    struct timespec tp = {.tv_sec = 0, .tv_nsec = 0};
 
-    if( 0 == clock_gettime(CLOCK_MONOTONIC, &tp) ) {
-        return (tp.tv_sec * 1e9 + tp.tv_nsec);
-    }
-    return 0;
+    (void) clock_gettime(CLOCK_MONOTONIC, &tp);
+
+    return (tp.tv_sec * 1e9 + tp.tv_nsec);
 }
 #endif  /* OPAL_HAVE_CLOCK_GETTIME */