diff mbox series

[4/5] selftests/powerpc/dscr: Speed up DSCR sysfs tests

Message ID 20230307005515.174362-5-bgray@linux.ibm.com (mailing list archive)
State Changes Requested
Headers show
Series Update DSCR tests | expand

Commit Message

Benjamin Gray March 7, 2023, 12:55 a.m. UTC 
This test case is extremely slow, taking around a minute compared to
most of the other DSCR tests taking a second at most. Perf shows most
time is spent by the kernel switching to each CPU it reads in
/sys/devices/system/cpu. This switching is an unavoidable consequnce
of reading all the .../cpuN/dscr values.

Remove the outer iteration loop from this test case, reducing the reads
from 1600 to 16. This still updates the DSCR 16 times and verifies on
every CPU each time, so I do not expect the lower coverage to be
meaningful. The speedup is significant: back down to ~1 second like the
other tests.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
---
 .../testing/selftests/powerpc/dscr/dscr_sysfs_test.c  | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
index 4f1fef6198fc..e7cd0d6b1fad 100644
--- a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
+++ b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
@@ -67,17 +67,14 @@  static int check_all_cpu_dscr_defaults(unsigned long val)
 int dscr_sysfs(void)
 {
 	unsigned long orig_dscr_default;
-	int i, j;
 
 	SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
 
 	orig_dscr_default = get_default_dscr();
-	for (i = 0; i < COUNT; i++) {
-		for (j = 0; j < DSCR_MAX; j++) {
-			set_default_dscr(j);
-			if (check_all_cpu_dscr_defaults(j))
-				goto fail;
-		}
+	for (int i = 0; i < DSCR_MAX; i++) {
+		set_default_dscr(i);
+		if (check_all_cpu_dscr_defaults(i))
+			goto fail;
 	}
 	set_default_dscr(orig_dscr_default);
 	return 0;