| Message ID | 46efa1f62e1604c98d10a1b6856a2b2aec0cfe9c.1725211324.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | selftests: vDSO: Build vDSO tests with O2 optimisation | expand |
On Sun, Sep 01, 2024 at 07:24:03PM +0200, Christophe Leroy wrote: > Without -O2, the generated code for testing chacha function is awful. > GCC even implements rol32() as a function instead of just using the > rotlwi instruction, that function is 20 instructions long. > > ~# time ./vdso_test_chacha > TAP version 13 > 1..1 > ok 1 chacha: PASS > real 0m 37.16s > user 0m 36.89s > sys 0m 0.26s > > Several other selftests directory add -O2, and the kernel is also > always built with optimisation active. Do the same for vDSO selftests. > > With this patch the time is reduced by approx 15%. > > ~# time ./vdso_test_chacha > TAP version 13 > 1..1 > ok 1 chacha: PASS > real 0m 32.09s > user 0m 31.86s > sys 0m 0.22s > Seems reasonable. I'll queue it up. Thanks. Jason
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile index cfb7c281b22c..96f25aa2f84e 100644 --- a/tools/testing/selftests/vDSO/Makefile +++ b/tools/testing/selftests/vDSO/Makefile @@ -13,7 +13,7 @@ TEST_GEN_PROGS += vdso_test_correctness TEST_GEN_PROGS += vdso_test_getrandom TEST_GEN_PROGS += vdso_test_chacha -CFLAGS := -std=gnu99 +CFLAGS := -std=gnu99 -O2 ifeq ($(CONFIG_X86_32),y) LDLIBS += -lgcc_s
Without -O2, the generated code for testing chacha function is awful. GCC even implements rol32() as a function instead of just using the rotlwi instruction, that function is 20 instructions long. ~# time ./vdso_test_chacha TAP version 13 1..1 ok 1 chacha: PASS real 0m 37.16s user 0m 36.89s sys 0m 0.26s Several other selftests directory add -O2, and the kernel is also always built with optimisation active. Do the same for vDSO selftests. With this patch the time is reduced by approx 15%. ~# time ./vdso_test_chacha TAP version 13 1..1 ok 1 chacha: PASS real 0m 32.09s user 0m 31.86s sys 0m 0.22s Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- tools/testing/selftests/vDSO/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)