@@ -38,8 +38,8 @@ 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,
- struct __kernel_timespec *ts)
+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];
u64 cycles, last, sec, ns;
@@ -68,8 +68,8 @@ 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,
- 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;
@@ -79,6 +79,8 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
ts->tv_sec = vdso_ts->sec;
ts->tv_nsec = vdso_ts->nsec;
} while (unlikely(vdso_read_retry(vd, seq)));
+
+ return 0;
}
static __maybe_unused int
@@ -96,15 +98,16 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
* clocks are handled in the VDSO directly.
*/
msk = 1U << clock;
- if (likely(msk & VDSO_HRES)) {
- return do_hres(&vd[CS_HRES_COARSE], 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);
- }
- return -1;
+ if (likely(msk & VDSO_HRES))
+ vd += CS_HRES_COARSE;
+ else if (msk & VDSO_COARSE)
+ return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
+ else if (msk & VDSO_RAW)
+ vd += CS_RAW;
+ else
+ return -1;
+
+ return do_hres(vd, clock, ts);
}
static __maybe_unused int
do_hres() is called from several places, so GCC doesn't inline it at first. do_hres() takes a struct __kernel_timespec * parameter for passing the result. In the 32 bits case, this parameter corresponds to a local var in the caller. In order to provide a pointer to this structure, the caller has to put it in its stack and do_hres() has to write the result in the stack. This is suboptimal, especially on RISC processor like powerpc. By making GCC inline the function, the struct __kernel_timespec remains a local var using registers, avoiding the need to write and read stack. The improvement is significant on powerpc: Before: gettimeofday: vdso: 1379 nsec/call clock-gettime-realtime-coarse: vdso: 868 nsec/call clock-gettime-realtime: vdso: 1511 nsec/call clock-gettime-monotonic-raw: vdso: 1576 nsec/call After: gettimeofday: vdso: 1078 nsec/call clock-gettime-realtime-coarse: vdso: 807 nsec/call clock-gettime-realtime: vdso: 1256 nsec/call clock-gettime-monotonic-raw: vdso: 1316 nsec/call At the same time, change the return type of do_coarse() to int, this increase readability of the if/elseif/elseif/else section in __cvdso_clock_gettime_common() Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- lib/vdso/gettimeofday.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-)