perf bench: Fix epoll bench to correct usage of affinity for machines with #CPUs...

The 'perf bench epoll' testcase fails on systems with more than 1K CPUs.

Testcase: perf bench epoll all

Result snippet:
<<>>
Run summary [PID 106497]: 1399 threads monitoring on 64 file-descriptors for 8 secs.

perf: pthread_create: No such file or directory
<<>>

In epoll benchmarks (ctl, wait) pthread_create is invoked in do_threads
from respective bench_epoll_*  function. Though the logs shows direct
failure from pthread_create, the actual failure is from
"sched_setaffinity" returning EINVAL (invalid argument).

This happens because the default mask size in glibc is 1024. To overcome
this 1024 CPUs mask size limitation of cpu_set_t, change the mask size
using the CPU_*_S macros.

Patch addresses this by fixing all the epoll benchmarks to use CPU_ALLOC
to allocate cpumask, CPU_ALLOC_SIZE for size, and CPU_SET_S to set the
mask.

Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nageswara R Sastry <rnsastry@linux.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20220406175113.87881-3-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/bench/epoll-ctl.c b/tools/perf/bench/epoll-ctl.c
index 134612b..4256dc5 100644 (file)
--- a/tools/perf/bench/epoll-ctl.c
+++ b/tools/perf/bench/epoll-ctl.c
@@ -222,13 +222,20 @@ static void init_fdmaps(struct worker *w, int pct)
 static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
 {
        pthread_attr_t thread_attr, *attrp = NULL;
-       cpu_set_t cpuset;
+       cpu_set_t *cpuset;
        unsigned int i, j;
        int ret = 0;
+       int nrcpus;
+       size_t size;
 
        if (!noaffinity)
                pthread_attr_init(&thread_attr);
 
+       nrcpus = perf_cpu_map__nr(cpu);
+       cpuset = CPU_ALLOC(nrcpus);
+       BUG_ON(!cpuset);
+       size = CPU_ALLOC_SIZE(nrcpus);
+
        for (i = 0; i < nthreads; i++) {
                struct worker *w = &worker[i];
 
@@ -252,22 +259,28 @@ static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
                        init_fdmaps(w, 50);
 
                if (!noaffinity) {
-                       CPU_ZERO(&cpuset);
-                       CPU_SET(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, &cpuset);
+                       CPU_ZERO_S(size, cpuset);
+                       CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu,
+                                       size, cpuset);
 
-                       ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset);
-                       if (ret)
+                       ret = pthread_attr_setaffinity_np(&thread_attr, size, cpuset);
+                       if (ret) {
+                               CPU_FREE(cpuset);
                                err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
+                       }
 
                        attrp = &thread_attr;
                }
 
                ret = pthread_create(&w->thread, attrp, workerfn,
                                     (void *)(struct worker *) w);
-               if (ret)
+               if (ret) {
+                       CPU_FREE(cpuset);
                        err(EXIT_FAILURE, "pthread_create");
+               }
        }
 
+       CPU_FREE(cpuset);
        if (!noaffinity)
                pthread_attr_destroy(&thread_attr);
 

diff --git a/tools/perf/bench/epoll-wait.c b/tools/perf/bench/epoll-wait.c
index 37de970..2728b01 100644 (file)
--- a/tools/perf/bench/epoll-wait.c
+++ b/tools/perf/bench/epoll-wait.c
@@ -291,9 +291,11 @@ static void print_summary(void)
 static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
 {
        pthread_attr_t thread_attr, *attrp = NULL;
-       cpu_set_t cpuset;
+       cpu_set_t *cpuset;
        unsigned int i, j;
        int ret = 0, events = EPOLLIN;
+       int nrcpus;
+       size_t size;
 
        if (oneshot)
                events |= EPOLLONESHOT;
@@ -306,6 +308,11 @@ static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
        if (!noaffinity)
                pthread_attr_init(&thread_attr);
 
+       nrcpus = perf_cpu_map__nr(cpu);
+       cpuset = CPU_ALLOC(nrcpus);
+       BUG_ON(!cpuset);
+       size = CPU_ALLOC_SIZE(nrcpus);
+
        for (i = 0; i < nthreads; i++) {
                struct worker *w = &worker[i];
 
@@ -341,22 +348,28 @@ static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
                }
 
                if (!noaffinity) {
-                       CPU_ZERO(&cpuset);
-                       CPU_SET(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, &cpuset);
+                       CPU_ZERO_S(size, cpuset);
+                       CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu,
+                                       size, cpuset);
 
-                       ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset);
-                       if (ret)
+                       ret = pthread_attr_setaffinity_np(&thread_attr, size, cpuset);
+                       if (ret) {
+                               CPU_FREE(cpuset);
                                err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
+                       }
 
                        attrp = &thread_attr;
                }
 
                ret = pthread_create(&w->thread, attrp, workerfn,
                                     (void *)(struct worker *) w);
-               if (ret)
+               if (ret) {
+                       CPU_FREE(cpuset);
                        err(EXIT_FAILURE, "pthread_create");
+               }
        }
 
+       CPU_FREE(cpuset);
        if (!noaffinity)
                pthread_attr_destroy(&thread_attr);