From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v4 3/3] kselftest: Extend vDSO selftest to clock_getres References: <20190523112116.19233-1-vincenzo.frascino@arm.com> <20190523112116.19233-4-vincenzo.frascino@arm.com> <87lfyrp0d2.fsf@concordia.ellerman.id.au> From: Vincenzo Frascino Message-ID: Date: Tue, 28 May 2019 12:57:24 +0100 MIME-Version: 1.0 In-Reply-To: <87lfyrp0d2.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kselftest-owner@vger.kernel.org List-ID: To: Michael Ellerman , linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , Shuah Khan , Thomas Gleixner , Arnd Bergmann Hi Michael, thank you for your reply. On 28/05/2019 07:19, Michael Ellerman wrote: > Vincenzo Frascino writes: > >> The current version of the multiarch vDSO selftest verifies only >> gettimeofday. >> >> Extend the vDSO selftest to clock_getres, to verify that the >> syscall and the vDSO library function return the same information. >> >> The extension has been used to verify the hrtimer_resoltion fix. > > This is passing for me even without patch 1 applied, shouldn't it fail > without the fix? What am I missing? > This is correct, because during the refactoring process I missed an "n" :) if·((x.tv_sec·!=·y.tv_sec)·||·(x.tv_sec·!=·y.tv_sec)) Should be: if·((x.tv_sec·!=·y.tv_sec)·||·(x.tv_nsec·!=·y.tv_nsec)) My mistake, I am going to fix the test and re-post v5 of this set. Without my patch if you pass "highres=off" to the kernel (as a command line parameter) it leads to a broken implementation of clock_getres since the value of CLOCK_REALTIME_RES does not change at runtime. Expected result (with highres=off): # uname -r 5.2.0-rc2 # ./vdso_clock_getres clock_id: CLOCK_REALTIME [FAIL] clock_id: CLOCK_BOOTTIME [PASS] clock_id: CLOCK_TAI [PASS] clock_id: CLOCK_REALTIME_COARSE [PASS] clock_id: CLOCK_MONOTONIC [FAIL] clock_id: CLOCK_MONOTONIC_RAW [PASS] clock_id: CLOCK_MONOTONIC_COARSE [PASS] The reason of this behavior is that the only clocks supported by getres on powerpc are CLOCK_REALTIME and CLOCK_MONOTONIC, the rest on the clocks use always syscalls. > # uname -r > 5.2.0-rc2-gcc-8.2.0 > > # ./vdso_clock_getres > clock_id: CLOCK_REALTIME [PASS] > clock_id: CLOCK_BOOTTIME [PASS] > clock_id: CLOCK_TAI [PASS] > clock_id: CLOCK_REALTIME_COARSE [PASS] > clock_id: CLOCK_MONOTONIC [PASS] > clock_id: CLOCK_MONOTONIC_RAW [PASS] > clock_id: CLOCK_MONOTONIC_COARSE [PASS] > > cheers > >> Cc: Shuah Khan >> Signed-off-by: Vincenzo Frascino >> --- >> >> Note: This patch is independent from the others in this series, hence it >> can be merged singularly by the kselftest maintainers. >> >> tools/testing/selftests/vDSO/Makefile | 2 + >> .../selftests/vDSO/vdso_clock_getres.c | 124 ++++++++++++++++++ >> 2 files changed, 126 insertions(+) >> create mode 100644 tools/testing/selftests/vDSO/vdso_clock_getres.c -- Regards, Vincenzo