| Context |
Check |
Description |
| snowpatch_ozlabs/apply_patch |
fail
|
Failed to apply to any branch
|
| snowpatch_ozlabs/apply_patch |
warning
|
Failed to apply on branch powerpc/merge (20862247a368dbb75d6e97d82345999adaacf3cc)
|
| snowpatch_ozlabs/apply_patch |
warning
|
Failed to apply on branch powerpc/next (3a9d970f17e05a7b26f782beb8f7f2118d1741ea)
|
| snowpatch_ozlabs/apply_patch |
warning
|
Failed to apply on branch linus/master (0c99ee44b8921b872089a7374c733310d995fd92)
|
| snowpatch_ozlabs/apply_patch |
warning
|
Failed to apply on branch powerpc/fixes (6da3eced8c5f3b03340b0c395bacd552c4d52411)
|
| snowpatch_ozlabs/apply_patch |
warning
|
Failed to apply on branch linux-next (2747d5fdab78f43210256cd52fb2718e0b3cce74)
|
@@ -95,6 +95,23 @@ static __always_inline u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 m
}
#define vdso_calc_delta vdso_calc_delta
+#ifndef __powerpc64__
+static __always_inline u64 vdso_shift_ns(u64 ns, unsigned long shift)
+{
+ u32 hi = ns >> 32;
+ u32 lo = ns;
+
+ lo = (lo >> shift) | (hi << (32 - shift));
+ hi >>= shift;
+
+ if (likely(hi == 0))
+ return lo;
+
+ return ((u64)hi << 32) | lo;
+}
+#define vdso_shift_ns vdso_shift_ns
+#endif
+
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
The generic x >> s gives the following result: 18: 35 25 ff e0 addic. r9,r5,-32 1c: 41 80 00 10 blt 2c <shift+0x14> 20: 7c 64 4c 30 srw r4,r3,r9 24: 38 60 00 00 li r3,0 ... 2c: 54 69 08 3c rlwinm r9,r3,1,0,30 30: 21 45 00 1f subfic r10,r5,31 34: 7c 84 2c 30 srw r4,r4,r5 38: 7d 29 50 30 slw r9,r9,r10 3c: 7c 63 2c 30 srw r3,r3,r5 40: 7d 24 23 78 or r4,r9,r4 In our case the shift is always < 32. In addition, the upper 32 bits of the result are likely nul. Lets GCC know it, it also optimises the following calculations. With the patch, we get: 0: 21 25 00 20 subfic r9,r5,32 4: 7c 69 48 30 slw r9,r3,r9 8: 7c 84 2c 30 srw r4,r4,r5 c: 7d 24 23 78 or r4,r9,r4 10: 7c 63 2c 30 srw r3,r3,r5 Performance before the patch: clock-gettime-realtime: vdso: 1033 nsec/call After the patch: clock-gettime-realtime: vdso: 941 nsec/call Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- arch/powerpc/include/asm/vdso/gettimeofday.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)