From 1b23d8b3a216cf0022401b22647ebed2eccc73e4 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Fri, 15 Oct 2021 12:57:43 +0200 Subject: [PATCH] openmp: Add support for OMP_PLACES=ll_caches This patch implements support for ll_caches abstract name in OMP_PLACES, which stands for places where logical cpus in each place share the last level cache. This seems to work fine for me on x86 and kernel sources show that it is in common code, but on some machines on CompileFarm the files I'm using, i.e. /sys/devices/system/cpu/cpuN/cache/indexN/level /sys/devices/system/cpu/cpuN/cache/indexN/shared_cpu_list don't exist, is that because they have too old kernel and newer kernels are fine or should I implement some fallback methods (which)? E.g. on gcc112.fsffrance.org I see just shared_cpu_map and not shared_cpu_list (with shared_cpu_map being harder to parse) and on another box I didn't even see the cache subdirectories. Way to test this is OMP_PLACES=ll_caches OMP_DISPLAY_ENV=true LD_PRELOAD=.libs/libgomp.so.1 /bin/true and see what it prints on OMP_PLACES line. 2021-10-15 Jakub Jelinek * env.c (parse_places_var): Handle ll_caches as level 4. * config/linux/affinity.c (gomp_affinity_find_last_cache_level): New function. (gomp_affinity_init_level_1): Handle level 4 as logical cpus sharing last level cache. (gomp_affinity_init_level): Likewise. * testsuite/libgomp.c/places-1.c: New test. * testsuite/libgomp.c/places-2.c: New test. * testsuite/libgomp.c/places-3.c: New test. * testsuite/libgomp.c/places-4.c: New test. (cherry picked from commit 5809be05a2813f2a95d9787f388185fa31fbf3a2) --- libgomp/ChangeLog.omp | 16 +++++++ libgomp/config/linux/affinity.c | 66 ++++++++++++++++++++++++-- libgomp/env.c | 5 ++ libgomp/testsuite/libgomp.c/places-1.c | 10 ++++ libgomp/testsuite/libgomp.c/places-2.c | 10 ++++ libgomp/testsuite/libgomp.c/places-3.c | 10 ++++ libgomp/testsuite/libgomp.c/places-4.c | 10 ++++ 7 files changed, 123 insertions(+), 4 deletions(-) create mode 100644 libgomp/testsuite/libgomp.c/places-1.c create mode 100644 libgomp/testsuite/libgomp.c/places-2.c create mode 100644 libgomp/testsuite/libgomp.c/places-3.c create mode 100644 libgomp/testsuite/libgomp.c/places-4.c diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp index f014b511ad99..af41b9293483 100644 --- a/libgomp/ChangeLog.omp +++ b/libgomp/ChangeLog.omp @@ -1,3 +1,19 @@ +2021-10-15 Tobias Burnus + + Backported from master: + 2021-10-15 Jakub Jelinek + + * env.c (parse_places_var): Handle ll_caches as level 4. + * config/linux/affinity.c (gomp_affinity_find_last_cache_level): New + function. + (gomp_affinity_init_level_1): Handle level 4 as logical cpus sharing + last level cache. + (gomp_affinity_init_level): Likewise. + * testsuite/libgomp.c/places-1.c: New test. + * testsuite/libgomp.c/places-2.c: New test. + * testsuite/libgomp.c/places-3.c: New test. + * testsuite/libgomp.c/places-4.c: New test. + 2021-10-15 Tobias Burnus Backported from master: diff --git a/libgomp/config/linux/affinity.c b/libgomp/config/linux/affinity.c index 1b636c613704..32415537853c 100644 --- a/libgomp/config/linux/affinity.c +++ b/libgomp/config/linux/affinity.c @@ -223,6 +223,46 @@ gomp_affinity_finalize_place_list (bool quiet) return true; } +/* Find the index of the last level cache. We assume the index + of the last level cache is the same for all logical CPUs. + Also, if there are multiple caches with the same highest level, + assume they have the same shared_cpu_list and pick the last one + from them (highest index number). */ + +static int +gomp_affinity_find_last_cache_level (char *name, size_t prefix_len, + unsigned long cpu) +{ + int ret = -1; + unsigned long maxval = 0; + char *line = NULL; + size_t linelen = 0; + FILE *f; + + for (int l = 0; l < 128; l++) + { + sprintf (name + prefix_len, "%lu/cache/index%u/level", cpu, l); + f = fopen (name, "r"); + if (f == NULL) + break; + if (getline (&line, &linelen, f) > 0) + { + unsigned long val; + char *p; + errno = 0; + val = strtoul (line, &p, 10); + if (!errno && val >= maxval) + { + ret = l; + maxval = val; + } + } + fclose (f); + } + free (line); + return ret; +} + static void gomp_affinity_init_level_1 (int level, int this_level, unsigned long count, cpu_set_t *copy, char *name, bool quiet) @@ -232,12 +272,29 @@ gomp_affinity_init_level_1 (int level, int this_level, unsigned long count, char *line = NULL; size_t linelen = 0; unsigned long i, max = 8 * gomp_cpuset_size; + int init = -1; for (i = 0; i < max && gomp_places_list_len < count; i++) if (CPU_ISSET_S (i, gomp_cpuset_size, copy)) { - sprintf (name + prefix_len, "%lu/topology/%s_siblings_list", - i, this_level == 3 ? "core" : "thread"); + if (level == 4) + { + if (init == -1) + { + init = gomp_affinity_find_last_cache_level (name, prefix_len, + i); + if (init == -1) + { + CPU_CLR_S (i, gomp_cpuset_size, copy); + continue; + } + sprintf (name + prefix_len, + "%lu/cache/index%u/shared_cpu_list", i, init); + } + } + else + sprintf (name + prefix_len, "%lu/topology/%s_siblings_list", + i, this_level == 3 ? "core" : "thread"); f = fopen (name, "r"); if (f == NULL) { @@ -302,7 +359,7 @@ bool gomp_affinity_init_level (int level, unsigned long count, bool quiet) { char name[sizeof ("/sys/devices/system/cpu/cpu/topology/" - "thread_siblings_list") + 3 * sizeof (unsigned long)]; + "thread_siblings_list") + 6 * sizeof (unsigned long)]; cpu_set_t *copy; if (gomp_cpusetp) @@ -320,7 +377,8 @@ gomp_affinity_init_level (int level, unsigned long count, bool quiet) copy = gomp_alloca (gomp_cpuset_size); strcpy (name, "/sys/devices/system/cpu/cpu"); memcpy (copy, gomp_cpusetp, gomp_cpuset_size); - gomp_affinity_init_level_1 (level, 3, count, copy, name, quiet); + gomp_affinity_init_level_1 (level, level > 3 ? level : 3, count, copy, name, + quiet); if (gomp_places_list_len == 0) { if (!quiet) diff --git a/libgomp/env.c b/libgomp/env.c index de45c25d540e..38903c76b344 100644 --- a/libgomp/env.c +++ b/libgomp/env.c @@ -696,6 +696,11 @@ parse_places_var (const char *name, bool ignore) env += 7; level = 3; } + else if (strncasecmp (env, "ll_caches", 9) == 0) + { + env += 9; + level = 4; + } if (level) { count = ULONG_MAX; diff --git a/libgomp/testsuite/libgomp.c/places-1.c b/libgomp/testsuite/libgomp.c/places-1.c new file mode 100644 index 000000000000..1d7c4676fdc7 --- /dev/null +++ b/libgomp/testsuite/libgomp.c/places-1.c @@ -0,0 +1,10 @@ +/* { dg-set-target-env-var OMP_PLACES "threads" } */ + +#include + +int +main () +{ + omp_display_env (0); + return 0; +} diff --git a/libgomp/testsuite/libgomp.c/places-2.c b/libgomp/testsuite/libgomp.c/places-2.c new file mode 100644 index 000000000000..4513eb6f3331 --- /dev/null +++ b/libgomp/testsuite/libgomp.c/places-2.c @@ -0,0 +1,10 @@ +/* { dg-set-target-env-var OMP_PLACES "cores" } */ + +#include + +int +main () +{ + omp_display_env (0); + return 0; +} diff --git a/libgomp/testsuite/libgomp.c/places-3.c b/libgomp/testsuite/libgomp.c/places-3.c new file mode 100644 index 000000000000..ddd994a6d7c2 --- /dev/null +++ b/libgomp/testsuite/libgomp.c/places-3.c @@ -0,0 +1,10 @@ +/* { dg-set-target-env-var OMP_PLACES "sockets" } */ + +#include + +int +main () +{ + omp_display_env (0); + return 0; +} diff --git a/libgomp/testsuite/libgomp.c/places-4.c b/libgomp/testsuite/libgomp.c/places-4.c new file mode 100644 index 000000000000..9e3d3e1b7d68 --- /dev/null +++ b/libgomp/testsuite/libgomp.c/places-4.c @@ -0,0 +1,10 @@ +/* { dg-set-target-env-var OMP_PLACES "ll_caches" } */ + +#include + +int +main () +{ + omp_display_env (0); + return 0; +} -- 2.47.2