From c14a9d0a79d4fb83c4e9e8cadc5cb094f41d01d0 Mon Sep 17 00:00:00 2001 From: Benjamin Gray Date: Thu, 6 Apr 2023 14:33:19 +1000 Subject: [PATCH] selftests/powerpc/dscr: Speed up DSCR sysfs tests 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 Signed-off-by: Michael Ellerman Link: https://msgid.link/20230406043320.125138-7-bgray@linux.ibm.com --- tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c index 4f1fef6..e7cd0d6 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; -- 2.7.4