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| author | Andy Lutomirski <luto@mit.edu> | 2012-03-22 21:15:51 -0700 |
|---|---|---|
| committer | John Stultz <john.stultz@linaro.org> | 2012-03-23 16:49:33 -0700 |
| commit | 91ec87d57fc38c529034e853687dfb7756de5406 (patch) | |
| tree | 4f88d6a7e0221bdd791a1de6d4c36b17da8337a2 /arch/x86/include/asm/vgtod.h | |
| parent | 88b28adf6fcdd6d10a1cfc7765bb200d7366a265 (diff) | |
| download | lwn-91ec87d57fc38c529034e853687dfb7756de5406.tar.gz lwn-91ec87d57fc38c529034e853687dfb7756de5406.zip | |
x86-64: Simplify and optimize vdso clock_gettime monotonic variants
We used to store the wall-to-monotonic offset and the realtime base.
It's faster to precompute the monotonic base.
This is about a 3% speedup on Sandy Bridge for CLOCK_MONOTONIC.
It's much more impressive for CLOCK_MONOTONIC_COARSE.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'arch/x86/include/asm/vgtod.h')
| -rw-r--r-- | arch/x86/include/asm/vgtod.h | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h index 1f007178c813..8b38be2de9e1 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -7,11 +7,6 @@ struct vsyscall_gtod_data { seqcount_t seq; - /* open coded 'struct timespec' */ - time_t wall_time_sec; - u32 wall_time_nsec; - - struct timezone sys_tz; struct { /* extract of a clocksource struct */ int vclock_mode; cycle_t cycle_last; @@ -19,8 +14,16 @@ struct vsyscall_gtod_data { u32 mult; u32 shift; } clock; - struct timespec wall_to_monotonic; + + /* open coded 'struct timespec' */ + time_t wall_time_sec; + u32 wall_time_nsec; + u32 monotonic_time_nsec; + time_t monotonic_time_sec; + + struct timezone sys_tz; struct timespec wall_time_coarse; + struct timespec monotonic_time_coarse; }; extern struct vsyscall_gtod_data vsyscall_gtod_data; |