Hi Pádraig,
The function 'num_processors' is now a bit large, and in particular contains
the multiplied complexity of
- the number of systems which each require a different approach,
- the query parameter which in one MUST consider omp_env_limit and in the
other case MAY but NEED NOT consider omp_env_limit.
To make this code more maintainable, I would propose to split it into
- a function which contains only the complexity of the various systems,
- a function which contains only the complexity of OMP handling.
Like this:
2017-02-26 Bruno Haible <***@clisp.org>
nproc: Refactor large function.
* lib/nproc.c (num_processors_ignoring_omp): New function, extracted
from num_processors.
(num_processors): In this function, only deal with OMP.
diff --git a/lib/nproc.c b/lib/nproc.c
index db3ca9b..7880e62 100644
--- a/lib/nproc.c
+++ b/lib/nproc.c
@@ -199,65 +199,12 @@ num_processors_via_affinity_mask (void)
return 0;
}
-/* Parse OMP environment variables without dependence on OMP.
- Return 0 for invalid values. */
-static unsigned long int
-parse_omp_threads (char const* threads)
-{
- unsigned long int ret = 0;
-
- if (threads == NULL)
- return ret;
-
- /* The OpenMP spec says that the value assigned to the environment variables
- "may have leading and trailing white space". */
- while (*threads != '\0' && c_isspace (*threads))
- threads++;
- /* Convert it from positive decimal to 'unsigned long'. */
- if (c_isdigit (*threads))
- {
- char *endptr = NULL;
- unsigned long int value = strtoul (threads, &endptr, 10);
-
- if (endptr != NULL)
- {
- while (*endptr != '\0' && c_isspace (*endptr))
- endptr++;
- if (*endptr == '\0')
- return value;
- /* Also accept the first value in a nesting level,
- since we can't determine the nesting level from env vars. */
- else if (*endptr == ',')
- return value;
- }
- }
-
- return ret;
-}
-
-unsigned long int
-num_processors (enum nproc_query query)
+/* Return the total number of processors. Here QUERY must be one of
+ NPROC_ALL, NPROC_CURRENT. The result is guaranteed to be at least 1. */
+static unsigned long int
+num_processors_ignoring_omp (enum nproc_query query)
{
- unsigned long int omp_env_limit = ULONG_MAX;
-
- if (query == NPROC_CURRENT_OVERRIDABLE)
- {
- unsigned long int omp_env_threads;
- /* Honor the OpenMP environment variables, recognized also by all
- programs that are based on OpenMP. */
- omp_env_threads = parse_omp_threads (getenv ("OMP_NUM_THREADS"));
- omp_env_limit = parse_omp_threads (getenv ("OMP_THREAD_LIMIT"));
- if (! omp_env_limit)
- omp_env_limit = ULONG_MAX;
-
- if (omp_env_threads)
- return MIN (omp_env_threads, omp_env_limit);
-
- query = NPROC_CURRENT;
- }
- /* Here query is one of NPROC_ALL, NPROC_CURRENT. */
-
/* On systems with a modern affinity mask system call, we have
sysconf (_SC_NPROCESSORS_CONF)
= sysconf (_SC_NPROCESSORS_ONLN)
@@ -279,7 +226,7 @@ num_processors (enum nproc_query query)
unsigned long nprocs = num_processors_via_affinity_mask ();
if (nprocs > 0)
- return MIN (nprocs, omp_env_limit);
+ return nprocs;
}
#if defined _SC_NPROCESSORS_ONLN
@@ -287,7 +234,7 @@ num_processors (enum nproc_query query)
Cygwin, Haiku. */
long int nprocs = sysconf (_SC_NPROCESSORS_ONLN);
if (nprocs > 0)
- return MIN (nprocs, omp_env_limit);
+ return nprocs;
}
#endif
}
@@ -330,7 +277,7 @@ num_processors (enum nproc_query query)
if (query == NPROC_CURRENT)
{
if (psd.psd_proc_cnt > 0)
- return MIN (psd.psd_proc_cnt, omp_env_limit);
+ return psd.psd_proc_cnt;
}
else
{
@@ -351,7 +298,7 @@ num_processors (enum nproc_query query)
? MP_NAPROCS
: MP_NPROCS);
if (nprocs > 0)
- return MIN (nprocs, omp_env_limit);
+ return nprocs;
}
#endif
@@ -367,7 +314,7 @@ num_processors (enum nproc_query query)
if (sysctl (mib, ARRAY_SIZE (mib), &nprocs, &len, NULL, 0) == 0
&& len == sizeof (nprocs)
&& 0 < nprocs)
- return MIN (nprocs, omp_env_limit);
+ return nprocs;
}
#endif
@@ -376,9 +323,73 @@ num_processors (enum nproc_query query)
SYSTEM_INFO system_info;
GetSystemInfo (&system_info);
if (0 < system_info.dwNumberOfProcessors)
- return MIN (system_info.dwNumberOfProcessors, omp_env_limit);
+ return system_info.dwNumberOfProcessors;
}
#endif
return 1;
}
+
+/* Parse OMP environment variables without dependence on OMP.
+ Return 0 for invalid values. */
+static unsigned long int
+parse_omp_threads (char const* threads)
+{
+ unsigned long int ret = 0;
+
+ if (threads == NULL)
+ return ret;
+
+ /* The OpenMP spec says that the value assigned to the environment variables
+ "may have leading and trailing white space". */
+ while (*threads != '\0' && c_isspace (*threads))
+ threads++;
+
+ /* Convert it from positive decimal to 'unsigned long'. */
+ if (c_isdigit (*threads))
+ {
+ char *endptr = NULL;
+ unsigned long int value = strtoul (threads, &endptr, 10);
+
+ if (endptr != NULL)
+ {
+ while (*endptr != '\0' && c_isspace (*endptr))
+ endptr++;
+ if (*endptr == '\0')
+ return value;
+ /* Also accept the first value in a nesting level,
+ since we can't determine the nesting level from env vars. */
+ else if (*endptr == ',')
+ return value;
+ }
+ }
+
+ return ret;
+}
+
+unsigned long int
+num_processors (enum nproc_query query)
+{
+ unsigned long int omp_env_limit = ULONG_MAX;
+
+ if (query == NPROC_CURRENT_OVERRIDABLE)
+ {
+ unsigned long int omp_env_threads;
+ /* Honor the OpenMP environment variables, recognized also by all
+ programs that are based on OpenMP. */
+ omp_env_threads = parse_omp_threads (getenv ("OMP_NUM_THREADS"));
+ omp_env_limit = parse_omp_threads (getenv ("OMP_THREAD_LIMIT"));
+ if (! omp_env_limit)
+ omp_env_limit = ULONG_MAX;
+
+ if (omp_env_threads)
+ return MIN (omp_env_threads, omp_env_limit);
+
+ query = NPROC_CURRENT;
+ }
+ /* Here query is one of NPROC_ALL, NPROC_CURRENT. */
+ {
+ unsigned long nprocs = num_processors_ignoring_omp (query);
+ return MIN (nprocs, omp_env_limit);
+ }
+}