diff --git a/examples/main.c b/examples/main.c
index b607791729ac0d419a227edae72814542898d931..ca3a696816369d6edac261bd3daa0fff31f84a91 100644
--- a/examples/main.c
+++ b/examples/main.c
@@ -52,6 +52,7 @@ void print_help_message() {
printf("\nUsage: swift [OPTION] PARAMFILE\n\n");
printf("Valid options are:\n");
+ printf(" %2s %8s %s\n", "-a", "[01]", "Use processor affinity");
printf(" %2s %8s %s\n", "-c", "", "Run with cosmological time integration");
printf(
" %2s %8s %s\n", "-d", "",
@@ -132,6 +133,7 @@ int main(int argc, char *argv[]) {
/* Welcome to SWIFT, you made the right choice */
if (myrank == 0) greetings();
+ int with_aff = 1;
int dry_run = 0;
int dump_tasks = 0;
int with_cosmology = 0;
@@ -146,7 +148,14 @@ int main(int argc, char *argv[]) {
/* Parse the parameters */
int c;
- while ((c = getopt(argc, argv, "cdef:gGhst:v:y:")) != -1) switch (c) {
+ while ((c = getopt(argc, argv, "a:cdef:gGhst:v:y:")) != -1) switch (c) {
+ case 'a':
+ if (sscanf(optarg, "%d", &with_aff) != 1) {
+ if (myrank == 0) printf("Error parsing affinity switch (-a).\n");
+ if (myrank == 0) print_help_message();
+ return 1;
+ }
+ break;
case 'c':
with_cosmology = 1;
break;
@@ -411,8 +420,9 @@ int main(int argc, char *argv[]) {
/* Initialize the engine with the space and policies. */
if (myrank == 0) clocks_gettime(&tic);
struct engine e;
- engine_init(&e, &s, params, nr_nodes, myrank, nr_threads, engine_policies,
- talking, &prog_const, &hydro_properties, &potential);
+ engine_init(&e, &s, params, nr_nodes, myrank, nr_threads, with_aff,
+ engine_policies, talking, &prog_const, &hydro_properties,
+ &potential);
if (myrank == 0) {
clocks_gettime(&toc);
message("engine_init took %.3f %s.", clocks_diff(&tic, &toc),
diff --git a/src/engine.c b/src/engine.c
index 31cc9abd629b08bf1575e2b92f0b3afd4d00d5df..9751b93fc81098f243505d2310d42a599b239683 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -2445,6 +2445,7 @@ void engine_unpin() {
* @param nr_nodes The number of MPI ranks.
* @param nodeID The MPI rank of this node.
* @param nr_threads The number of threads per MPI rank.
+ * @param with_aff use processor affinity, if supported.
* @param policy The queuing policy to use.
* @param verbose Is this #engine talkative ?
* @param physical_constants The #phys_const used for this run.
@@ -2454,7 +2455,7 @@ void engine_unpin() {
void engine_init(struct engine *e, struct space *s,
const struct swift_params *params, int nr_nodes, int nodeID,
- int nr_threads, int policy, int verbose,
+ int nr_threads, int with_aff, int policy, int verbose,
const struct phys_const *physical_constants,
const struct hydro_props *hydro,
const struct external_potential *potential) {
@@ -2527,7 +2528,7 @@ void engine_init(struct engine *e, struct space *s,
buf[j] = CPU_ISSET(j, entry_affinity) ? '1' : '0';
}
- if (verbose) message("Affinity at entry: %s", buf);
+ if (verbose && with_aff) message("Affinity at entry: %s", buf);
int *cpuid = malloc(nr_affinity_cores * sizeof(int));
cpu_set_t cpuset;
@@ -2541,51 +2542,87 @@ void engine_init(struct engine *e, struct space *s,
skip = c + 1;
}
+ if (with_aff) {
+
#if defined(HAVE_LIBNUMA) && defined(_GNU_SOURCE)
- if ((policy & engine_policy_cputight) != engine_policy_cputight) {
- /* Ascending NUMA distance. Bubblesort(!) for stable equidistant CPUs. */
- if (numa_available() >= 0) {
- if (nodeID == 0) message("prefer NUMA-local CPUs");
-
- const int home = numa_node_of_cpu(sched_getcpu());
- int done = 0;
-
- while (!done) {
- done = 1;
- for (int i = 1; i < nr_affinity_cores; i++) {
- const int node_a = numa_node_of_cpu(cpuid[i - 1]);
- const int node_b = numa_node_of_cpu(cpuid[i]);
-
- const int swap =
- numa_distance(home, node_a) > numa_distance(home, node_b);
-
- if (swap) {
- const int t = cpuid[i - 1];
- cpuid[i - 1] = cpuid[i];
- cpuid[i] = t;
- done = 0;
+ if ((policy & engine_policy_cputight) != engine_policy_cputight) {
+
+ if (numa_available() >= 0) {
+ if (nodeID == 0) message("prefer NUMA-distant CPUs");
+
+ /* Get list of numa nodes of all available cores. */
+ int *nodes = malloc( nr_affinity_cores * sizeof(int));
+ int nnodes = 0;
+ for (int i = 0; i < nr_affinity_cores; i++) {
+ nodes[i] = numa_node_of_cpu(cpuid[i]);
+ if (nodes[i] > nnodes) nnodes = nodes[i];
+ }
+ nnodes += 1;
+
+ /* Count cores per node. */
+ int *core_counts = malloc( nnodes * sizeof(int));
+ for (int i = 0; i < nr_affinity_cores; i++) {
+ core_counts[nodes[i]] = 0;
+ }
+ for (int i = 0; i < nr_affinity_cores; i++) {
+ core_counts[nodes[i]] += 1;
+ }
+
+ /* Index cores within each node. */
+ int *core_indices = malloc( nr_affinity_cores * sizeof(int));
+ for (int i = nr_affinity_cores - 1; i >= 0; i--) {
+ core_indices[i] = core_counts[nodes[i]];
+ core_counts[nodes[i]] -= 1;
+ }
+
+ /* Now sort so that we pick adjacent cpuids from different nodes
+ * by sorting internal node core indices. */
+ int done = 0;
+ while (!done) {
+ done = 1;
+ for (int i = 1; i < nr_affinity_cores; i++) {
+ if ( core_indices[i] < core_indices[i-1] ) {
+ int t = cpuid[i-1];
+ cpuid[i-1] = cpuid[i];
+ cpuid[i] = t;
+
+ t = core_indices[i-1];
+ core_indices[i-1] = core_indices[i];
+ core_indices[i] = t;
+ done = 0;
+ }
}
}
+
+ free(nodes);
+ free(core_counts);
+ free(core_indices);
}
}
- }
#endif
+ }
+ else {
+ if (nodeID == 0) message("no processor affinity used");
+
+ }/* with_aff */
/* Avoid (unexpected) interference between engine and runner threads. We can
* do this once we've made at least one call to engine_entry_affinity and
* maybe numa_node_of_cpu(sched_getcpu()), even if the engine isn't already
- * pinned. */
+ * pinned. Also unpin this when asked to not pin at all (!with_aff). */
engine_unpin();
#endif
+ if (with_aff) {
#ifdef WITH_MPI
- printf("[%04i] %s engine_init: cpu map is [ ", nodeID,
- clocks_get_timesincestart());
+ printf("[%04i] %s engine_init: cpu map is [ ", nodeID,
+ clocks_get_timesincestart());
#else
- printf("%s engine_init: cpu map is [ ", clocks_get_timesincestart());
+ printf("%s engine_init: cpu map is [ ", clocks_get_timesincestart());
#endif
- for (int i = 0; i < nr_affinity_cores; i++) printf("%i ", cpuid[i]);
- printf("].\n");
+ for (int i = 0; i < nr_affinity_cores; i++) printf("%i ", cpuid[i]);
+ printf("].\n");
+ }
/* Are we doing stuff in parallel? */
if (nr_nodes > 1) {
@@ -2730,12 +2767,13 @@ void engine_init(struct engine *e, struct space *s,
error("Failed to create runner thread.");
/* Try to pin the runner to a given core */
- if ((e->policy & engine_policy_setaffinity) == engine_policy_setaffinity) {
+ if (with_aff && (e->policy & engine_policy_setaffinity) == engine_policy_setaffinity) {
#if defined(HAVE_SETAFFINITY)
/* Set a reasonable queue ID. */
int coreid = k % nr_affinity_cores;
e->runners[k].cpuid = cpuid[coreid];
+
if (nr_queues < e->nr_threads)
e->runners[k].qid = cpuid[coreid] * nr_queues / nr_affinity_cores;
else
@@ -2757,15 +2795,22 @@ void engine_init(struct engine *e, struct space *s,
e->runners[k].cpuid = k;
e->runners[k].qid = k * nr_queues / e->nr_threads;
}
- if (verbose)
- message("runner %i on cpuid=%i with qid=%i.", e->runners[k].id,
- e->runners[k].cpuid, e->runners[k].qid);
+ if (verbose) {
+ if (with_aff)
+ message("runner %i on cpuid=%i with qid=%i.", e->runners[k].id,
+ e->runners[k].cpuid, e->runners[k].qid);
+ else
+ message("runner %i using qid=%i no cpuid.", e->runners[k].id,
+ e->runners[k].qid);
+ }
}
/* Free the affinity stuff */
#if defined(HAVE_SETAFFINITY)
- free(cpuid);
- free(buf);
+ if (with_aff) {
+ free(cpuid);
+ free(buf);
+ }
#endif
/* Wait for the runner threads to be in place. */
diff --git a/src/engine.h b/src/engine.h
index 15abc4b6393fec97582e2ec3c7551f5f64f9a0e4..6e7987ee9ec35727a2b889dba8a6fb8ee4da6088 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -197,7 +197,7 @@ void engine_compute_next_snapshot_time(struct engine *e);
void engine_dump_snapshot(struct engine *e);
void engine_init(struct engine *e, struct space *s,
const struct swift_params *params, int nr_nodes, int nodeID,
- int nr_threads, int policy, int verbose,
+ int nr_threads, int with_aff, int policy, int verbose,
const struct phys_const *physical_constants,
const struct hydro_props *hydro,
const struct external_potential *potential);