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Deduce automatically number of cores for -flto option.
2019-07-30 Martin Liska <mliska@suse.cz> * doc/invoke.texi: Document new behavior. * lto-wrapper.c (cpuset_popcount): New function is a copy of libgomp/config/linux/proc.c. (init_num_threads): Likewise. (run_gcc): Automatically detect core count for -flto. (jobserver_active_p): New function. From-SVN: r273908
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Martin Liska
Martin Liska
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200b0e7e82
@ -1,3 +1,12 @@
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2019-07-30 Martin Liska <mliska@suse.cz>
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* doc/invoke.texi: Document new behavior.
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* lto-wrapper.c (cpuset_popcount): New function
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is a copy of libgomp/config/linux/proc.c.
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(init_num_threads): Likewise.
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(run_gcc): Automatically detect core count for -flto.
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(jobserver_active_p): New function.
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2019-07-30 Richard Biener <rguenther@suse.de>
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PR tree-optimization/91257
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@ -10396,7 +10396,8 @@ If you specify the optional @var{n}, the optimization and code
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generation done at link time is executed in parallel using @var{n}
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parallel jobs by utilizing an installed @command{make} program. The
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environment variable @env{MAKE} may be used to override the program
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used. The default value for @var{n} is 1.
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used. The default value for @var{n} is automatically detected based
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on number of cores.
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You can also specify @option{-flto=jobserver} to use GNU make's
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job server mode to determine the number of parallel jobs. This
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@ -1110,6 +1110,136 @@ cmp_priority (const void *a, const void *b)
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return *((const int *)b)-*((const int *)a);
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}
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/* Number of CPUs that can be used for parallel LTRANS phase. */
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static unsigned long nthreads_var = 0;
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#ifdef HAVE_PTHREAD_AFFINITY_NP
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unsigned long cpuset_size;
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static unsigned long get_cpuset_size;
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cpu_set_t *cpusetp;
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unsigned long
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static cpuset_popcount (unsigned long cpusetsize, cpu_set_t *cpusetp)
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{
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#ifdef CPU_COUNT_S
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/* glibc 2.7 and above provide a macro for this. */
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return CPU_COUNT_S (cpusetsize, cpusetp);
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#else
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#ifdef CPU_COUNT
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if (cpusetsize == sizeof (cpu_set_t))
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/* glibc 2.6 and above provide a macro for this. */
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return CPU_COUNT (cpusetp);
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#endif
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size_t i;
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unsigned long ret = 0;
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STATIC_ASSERT (sizeof (cpusetp->__bits[0]) == sizeof (unsigned long int));
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for (i = 0; i < cpusetsize / sizeof (cpusetp->__bits[0]); i++)
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{
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unsigned long int mask = cpusetp->__bits[i];
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if (mask == 0)
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continue;
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ret += __builtin_popcountl (mask);
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}
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return ret;
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#endif
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}
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#endif
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/* At startup, determine the default number of threads. It would seem
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this should be related to the number of cpus online. */
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static void
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init_num_threads (void)
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{
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#ifdef HAVE_PTHREAD_AFFINITY_NP
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#if defined (_SC_NPROCESSORS_CONF) && defined (CPU_ALLOC_SIZE)
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cpuset_size = sysconf (_SC_NPROCESSORS_CONF);
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cpuset_size = CPU_ALLOC_SIZE (cpuset_size);
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#else
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cpuset_size = sizeof (cpu_set_t);
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#endif
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cpusetp = (cpu_set_t *) xmalloc (gomp_cpuset_size);
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do
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{
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int ret = pthread_getaffinity_np (pthread_self (), gomp_cpuset_size,
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cpusetp);
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if (ret == 0)
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{
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/* Count only the CPUs this process can use. */
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nthreads_var = cpuset_popcount (cpuset_size, cpusetp);
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if (nthreads_var == 0)
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break;
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get_cpuset_size = cpuset_size;
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#ifdef CPU_ALLOC_SIZE
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unsigned long i;
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for (i = cpuset_size * 8; i; i--)
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if (CPU_ISSET_S (i - 1, cpuset_size, cpusetp))
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break;
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cpuset_size = CPU_ALLOC_SIZE (i);
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#endif
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return;
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}
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if (ret != EINVAL)
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break;
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#ifdef CPU_ALLOC_SIZE
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if (cpuset_size < sizeof (cpu_set_t))
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cpuset_size = sizeof (cpu_set_t);
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else
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cpuset_size = cpuset_size * 2;
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if (cpuset_size < 8 * sizeof (cpu_set_t))
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cpusetp
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= (cpu_set_t *) realloc (cpusetp, cpuset_size);
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else
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{
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/* Avoid fatal if too large memory allocation would be
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requested, e.g. kernel returning EINVAL all the time. */
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void *p = realloc (cpusetp, cpuset_size);
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if (p == NULL)
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break;
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cpusetp = (cpu_set_t *) p;
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}
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#else
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break;
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#endif
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}
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while (1);
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cpuset_size = 0;
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nthreads_var = 1;
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free (cpusetp);
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cpusetp = NULL;
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#endif
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#ifdef _SC_NPROCESSORS_ONLN
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nthreads_var = sysconf (_SC_NPROCESSORS_ONLN);
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#endif
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}
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/* FIXME: once using -std=c11, we can use std::thread::hardware_concurrency. */
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/* Return true when a jobserver is running and can accept a job. */
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static bool
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jobserver_active_p (void)
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{
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const char *makeflags = getenv ("MAKEFLAGS");
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if (makeflags == NULL)
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return false;
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const char *needle = "--jobserver-auth=";
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const char *n = strstr (makeflags, needle);
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if (n == NULL)
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return false;
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int rfd = -1;
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int wfd = -1;
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return ((sscanf(n, "--jobserver-auth=%d,%d", &rfd, &wfd) == 2)
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&& rfd > 0
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&& wfd > 0
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&& fcntl (rfd, F_GETFD) >= 0
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&& fcntl (wfd, F_GETFD) >= 0);
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}
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/* Execute gcc. ARGC is the number of arguments. ARGV contains the arguments. */
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@ -1122,8 +1252,10 @@ run_gcc (unsigned argc, char *argv[])
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char *list_option_full = NULL;
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const char *linker_output = NULL;
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const char *collect_gcc, *collect_gcc_options;
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int parallel = 0;
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/* Make linking parallel by default. */
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int parallel = 1;
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int jobserver = 0;
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int auto_parallel = 0;
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bool no_partition = false;
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struct cl_decoded_option *fdecoded_options = NULL;
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struct cl_decoded_option *offload_fdecoded_options = NULL;
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@ -1247,10 +1379,7 @@ run_gcc (unsigned argc, char *argv[])
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case OPT_flto_:
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if (strcmp (option->arg, "jobserver") == 0)
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{
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jobserver = 1;
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parallel = 1;
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}
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jobserver = 1;
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else
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{
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parallel = atoi (option->arg);
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@ -1291,8 +1420,17 @@ run_gcc (unsigned argc, char *argv[])
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{
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lto_mode = LTO_MODE_LTO;
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jobserver = 0;
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auto_parallel = 0;
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parallel = 0;
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}
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else if (!jobserver && parallel)
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{
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/* If there's no explicit usage of jobserver and
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parallel is enabled, then automatically detect
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jobserver or number of cores. */
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auto_parallel = 1;
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jobserver = jobserver_active_p ();
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}
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if (linker_output)
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{
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@ -1484,7 +1622,21 @@ cont1:
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strcpy (tmp, ltrans_output_file);
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if (jobserver)
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obstack_ptr_grow (&argv_obstack, xstrdup ("-fwpa=jobserver"));
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{
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if (verbose)
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fprintf (stderr, "Using make jobserver\n");
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obstack_ptr_grow (&argv_obstack, xstrdup ("-fwpa=jobserver"));
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}
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else if (auto_parallel)
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{
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char buf[256];
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init_num_threads ();
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if (verbose)
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fprintf (stderr, "LTO parallelism level set to %ld\n",
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nthreads_var);
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sprintf (buf, "-fwpa=%ld", nthreads_var);
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obstack_ptr_grow (&argv_obstack, xstrdup (buf));
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}
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else if (parallel > 1)
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{
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char buf[256];
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@ -1692,7 +1844,8 @@ cont:
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i = 3;
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if (!jobserver)
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{
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snprintf (jobs, 31, "-j%d", parallel);
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snprintf (jobs, 31, "-j%ld",
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auto_parallel ? nthreads_var : parallel);
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new_argv[i++] = jobs;
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}
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new_argv[i++] = "all";
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