Merge pull request #406 from carns/carns/issue-404-timedwait-doc

note about CPU utilization of ABT_cond_timedwait()

Author: mdorier

src/cond.c

@@ -222,6 +222,14 @@ int ABT_cond_wait(ABT_cond cond, ABT_mutex mutex)
  * Unlike other implementations of condition variables, a spurious wakeup never
  * occurs.
  *
+ * @note
+ * This function exhibits significantly higher CPU utilization than
+ * ABT_cond_wait() when blocking, even with the BASIC_WAIT scheduler. This
+ * is because Argobots lacks a user-space timeout mechanism, requiring
+ * continuous rescheduling of the caller to poll for `abstime`. The
+ * `--enable-sched-sleep` option can mitigate this, but it introduces a
+ * latency penalty for some workloads.
+ *
  * @contexts
  * \DOC_CONTEXT_ANY \DOC_CONTEXT_CTXSWITCH
  *

src/include/abti_error.h

@@ -34,7 +34,7 @@
 
 #define ABTI_STATIC_ASSERT(cond)                                               \
     do {                                                                       \
-        ((void)sizeof(char[2 * !!(cond)-1]));                                  \
+        ((void)sizeof(char[2 * !!(cond) - 1]));                                \
     } while (0)
 
 #ifdef ABT_CONFIG_PRINT_ABT_ERRNO

test/basic/info_query.c

@@ -56,7 +56,7 @@ void info_query_all(ABT_bool init)
     while (p_query) {
         if (!(p_query->need_init && !init)) {
             const int idx = p_query->buffer_idx++;
-            int32_t *ptr = (int32_t *)(&p_query->buffers[1 + (idx)*3]);
+            int32_t *ptr = (int32_t *)(&p_query->buffers[1 + (idx) * 3]);
             ptr[-1] = 0x77777777;
             ptr[0] = 0x77777777;
             ptr[1] = 0x77777777;

test/benchmark/thread_ops.c

@@ -8,7 +8,7 @@
 #include "abt.h"
 #include "abttest.h"
 
-//#define TEST_MIGRATE_TO
+// #define TEST_MIGRATE_TO
 #define USE_JOIN_MANY
 #ifdef USE_JOIN_MANY
 #define ABT_THREAD_JOIN_MANY(n, tl) ABT_thread_join_many(n, tl)

test/benchmark/thread_ops_all.c

@@ -8,7 +8,7 @@
 #include "abt.h"
 #include "abttest.h"
 
-//#define TEST_MIGRATE_TO
+// #define TEST_MIGRATE_TO
 #define USE_JOIN_MANY
 #ifdef USE_JOIN_MANY
 #define ABT_THREAD_JOIN_MANY(n, tl) ABT_thread_join_many(n, tl)