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authorMark Brown <broonie@kernel.org>2022-11-30 00:59:25 +0300
committerWill Deacon <will@kernel.org>2022-12-01 20:46:45 +0300
commitc4e8720f2eb0c7f59082f41ad73b82e5d3f19f69 (patch)
treef015b87257dcad01491e2b7d168f2f0f1087f0d7 /tools/testing
parent92145d88ce0b216c1b99aaac92fec1f6a7d6ddde (diff)
downloadlinux-c4e8720f2eb0c7f59082f41ad73b82e5d3f19f69.tar.xz
kselftest/arm64: Allow epoll_wait() to return more than one result
When everything is starting up we are likely to have a lot of child processes producing output at once. This means that we can reduce overhead a bit by allowing epoll_wait() to return more than one descriptor at once, it cuts down on the number of system calls we need to do which on virtual platforms where the syscall overhead is a bit more noticable and we're likely to have a lot more children active can make a small but noticable difference. On physical platforms the relatively small number of processes being run and vastly improved speeds push the effects of this change into the noise. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20221129215926.442895-4-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'tools/testing')
-rw-r--r--tools/testing/selftests/arm64/fp/fp-stress.c27
1 files changed, 18 insertions, 9 deletions
diff --git a/tools/testing/selftests/arm64/fp/fp-stress.c b/tools/testing/selftests/arm64/fp/fp-stress.c
index b3bbfe8d9f56..f8b2f41aac36 100644
--- a/tools/testing/selftests/arm64/fp/fp-stress.c
+++ b/tools/testing/selftests/arm64/fp/fp-stress.c
@@ -39,6 +39,8 @@ struct child_data {
static int epoll_fd;
static struct child_data *children;
+static struct epoll_event *evs;
+static int tests;
static int num_children;
static bool terminate;
@@ -393,11 +395,11 @@ static void probe_vls(int vls[], int *vl_count, int set_vl)
/* Handle any pending output without blocking */
static void drain_output(bool flush)
{
- struct epoll_event ev;
int ret = 1;
+ int i;
while (ret > 0) {
- ret = epoll_wait(epoll_fd, &ev, 1, 0);
+ ret = epoll_wait(epoll_fd, evs, tests, 0);
if (ret < 0) {
if (errno == EINTR)
continue;
@@ -405,8 +407,8 @@ static void drain_output(bool flush)
strerror(errno), errno);
}
- if (ret == 1)
- child_output(ev.data.ptr, ev.events, flush);
+ for (i = 0; i < ret; i++)
+ child_output(evs[i].data.ptr, evs[i].events, flush);
}
}
@@ -419,12 +421,11 @@ int main(int argc, char **argv)
{
int ret;
int timeout = 10;
- int cpus, tests, i, j, c;
+ int cpus, i, j, c;
int sve_vl_count, sme_vl_count, fpsimd_per_cpu;
bool all_children_started = false;
int seen_children;
int sve_vls[MAX_VLS], sme_vls[MAX_VLS];
- struct epoll_event ev;
struct sigaction sa;
while ((c = getopt_long(argc, argv, "t:", options, NULL)) != -1) {
@@ -510,6 +511,11 @@ int main(int argc, char **argv)
ksft_print_msg("Failed to install SIGCHLD handler: %s (%d)\n",
strerror(errno), errno);
+ evs = calloc(tests, sizeof(*evs));
+ if (!evs)
+ ksft_exit_fail_msg("Failed to allocated %d epoll events\n",
+ tests);
+
for (i = 0; i < cpus; i++) {
for (j = 0; j < fpsimd_per_cpu; j++)
start_fpsimd(&children[num_children++], i, j);
@@ -543,7 +549,7 @@ int main(int argc, char **argv)
* useful in emulation where we will both be slow and
* likely to have a large set of VLs.
*/
- ret = epoll_wait(epoll_fd, &ev, 1, 1000);
+ ret = epoll_wait(epoll_fd, evs, tests, 1000);
if (ret < 0) {
if (errno == EINTR)
continue;
@@ -552,8 +558,11 @@ int main(int argc, char **argv)
}
/* Output? */
- if (ret == 1) {
- child_output(ev.data.ptr, ev.events, false);
+ if (ret > 0) {
+ for (i = 0; i < ret; i++) {
+ child_output(evs[i].data.ptr, evs[i].events,
+ false);
+ }
continue;
}