[PATCHv8 02/34] lib/vdso: make do_hres and do_coarse as __always_inline

Dmitry Safonov
2019-11-12T01:26:51Z

From: Andrei Vagin <avagin@gmail.com>

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%

Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
lib/vdso/gettimeofday.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 45f57fd2db64..9923e1eab9db 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];
@@ -68,7 +68,7 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
return 0;
}

-static void do_coarse(const struct vdso_data *vd, clockid_t clk,
+static __always_inline void do_coarse(const struct vdso_data *vd, clockid_t clk,
struct __kernel_timespec *ts)
{
const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
@@ -97,12 +97,16 @@ __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];
+out_hres:
+ return do_hres(vd, clock, ts);
} else if (msk & VDSO_COARSE) {
do_coarse(&vd[CS_HRES_COARSE], clock, ts);
return 0;
} else if (msk & VDSO_RAW) {
- return do_hres(&vd[CS_RAW], clock, ts);
+ vd = &vd[CS_RAW];
+ /* goto allows to avoid extra inlining of do_hres. */
+ goto out_hres;
}
return -1;
}
--
2.24.0