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Subject[tip: timers/core] lib/vdso: Mark do_hres() and do_coarse() as __always_inline
The following commit has been merged into the timers/core branch of tip:

Commit-ID: c966533f8c6c45f93c52599f8460e7695f0b7eaa
Gitweb: https://git.kernel.org/tip/c966533f8c6c45f93c52599f8460e7695f0b7eaa
Author: Andrei Vagin <avagin@gmail.com>
AuthorDate: Tue, 12 Nov 2019 01:26:51
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 14 Jan 2020 12:20:48 +01:00

lib/vdso: Mark do_hres() and do_coarse() as __always_inline

Performance numbers for Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
(more clock_gettime() cycles - the better):

clock | before | after | diff
----------------------------------------------------------
monotonic | 153222105 | 166775025 | 8.8%
monotonic-coarse | 671557054 | 691513017 | 3.0%
monotonic-raw | 147116067 | 161057395 | 9.5%
boottime | 153446224 | 166962668 | 9.1%

The improvement for arm64 for monotonic and boottime is around 3.5%.

clock | before | after | diff
==================================================
monotonic 17326692 17951770 3.6%
monotonic-coarse 43624027 44215292 1.3%
monotonic-raw 17541809 17554932 0.1%
boottime 17334982 17954361 3.5%

[ tglx: Avoid the goto ]

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-3-dima@arista.com


---
lib/vdso/gettimeofday.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index fac9e86..b453d24 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -38,7 +38,7 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
}
#endif

-static int do_hres(const struct vdso_data *vd, clockid_t clk,
+static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
struct __kernel_timespec *ts)
{
const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
@@ -68,8 +68,8 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
return 0;
}

-static int do_coarse(const struct vdso_data *vd, clockid_t clk,
- struct __kernel_timespec *ts)
+static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
+ struct __kernel_timespec *ts)
{
const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
u32 seq;
@@ -99,13 +99,15 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
*/
msk = 1U << clock;
if (likely(msk & VDSO_HRES))
- return do_hres(&vd[CS_HRES_COARSE], clock, ts);
+ vd = &vd[CS_HRES_COARSE];
else if (msk & VDSO_COARSE)
return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
else if (msk & VDSO_RAW)
- return do_hres(&vd[CS_RAW], clock, ts);
+ vd = &vd[CS_RAW];
+ else
+ return -1;

- return -1;
+ return do_hres(vd, clock, ts);
}

static __maybe_unused int
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