diff options
| author | Mark Salyzyn <salyzyn@google.com> | 2017-08-24 13:35:24 -0700 |
|---|---|---|
| committer | Michael Bestas <mkbestas@lineageos.org> | 2019-12-23 23:43:39 +0200 |
| commit | 53834fd2b3866e4a08fb34cbf0d5b2fe6b38617c (patch) | |
| tree | 4696d3ba67f52c8d0ae10cf60d2d0325c163e18e /arch/arm/kernel | |
| parent | b0c38eea4bdbd7bdad296144fdbbe8c1e588e09a (diff) | |
FROMLIST: [PATCH v5 11/12] lib: vdso: Add support for CLOCK_BOOTTIME
(cherry pick from url https://patchwork.kernel.org/patch/10044503/)
Take an effort to recode the arm64 vdso code from assembler to C
previously submitted by Andrew Pinski <apinski@cavium.com>, rework
it for use in both arm and arm64, overlapping any optimizations
for each architecture. But instead of landing it in arm64, land the
result into lib/vdso and unify both implementations to simplify
future maintenance.
Add a case for CLOCK_BOOTTIME as it is popular for measuring
relative time on systems expected to suspend() or hibernate().
Android uses CLOCK_BOOTTIME for all relative time measurements
and timeouts. Switching to vdso reduced CPU utilization and improves
accuracy. There is also a desire by some partners to switch all
logging over to CLOCK_BOOTTIME, and thus this operation alone would
contribute to a near percentile CPU load.
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: James Morse <james.morse@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Andrew Pinski <apinski@cavium.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Bug: 63737556
Bug: 20045882
Change-Id: I76c26b054baf7f1100e03c65d6b16fe649b883b1
Diffstat (limited to 'arch/arm/kernel')
| -rw-r--r-- | arch/arm/kernel/vdso.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c index b78f9eb792ca..36159e95eff4 100644 --- a/arch/arm/kernel/vdso.c +++ b/arch/arm/kernel/vdso.c @@ -329,6 +329,7 @@ void update_vsyscall(struct timekeeper *tk) /* tkr_mono.shift == tkr_raw.shift */ vdso_data->cs_shift = tk->tkr_mono.shift; vdso_data->cs_mask = tk->tkr_mono.mask; + vdso_data->btm_nsec = ktime_to_ns(tk->offs_boot); } vdso_write_end(vdso_data); |