diff options
| author | Paul Mackerras <paulus@samba.org> | 2008-10-27 23:56:03 +0000 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2008-11-06 09:49:22 +1100 |
| commit | 597bc5c00b666fe123abb0af64f6e86f7ab72a90 (patch) | |
| tree | f6be6e6f07fb1caff3b670a7ac3df74a621ae364 /arch/powerpc/include | |
| parent | c73049f6aa58ac1d1a9ca8cb2b415ef97240b2d3 (diff) | |
powerpc: Improve resolution of VDSO clock_gettime
Currently the clock_gettime implementation in the VDSO produces a
result with microsecond resolution for the cases that are handled
without a system call, i.e. CLOCK_REALTIME and CLOCK_MONOTONIC. The
nanoseconds field of the result is obtained by computing a
microseconds value and multiplying by 1000.
This changes the code in the VDSO to do the computation for
clock_gettime with nanosecond resolution. That means that the
resolution of the result will ultimately depend on the timebase
frequency.
Because the timestamp in the VDSO datapage (stamp_xsec, the real time
corresponding to the timebase count in tb_orig_stamp) is in units of
2^-20 seconds, it doesn't have sufficient resolution for computing a
result with nanosecond resolution. Therefore this adds a copy of
xtime to the VDSO datapage and updates it in update_gtod() along with
the other time-related fields.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/asm/vdso_datapage.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h index f01393224b5..13c2c283e17 100644 --- a/arch/powerpc/include/asm/vdso_datapage.h +++ b/arch/powerpc/include/asm/vdso_datapage.h @@ -39,6 +39,7 @@ #ifndef __ASSEMBLY__ #include <linux/unistd.h> +#include <linux/time.h> #define SYSCALL_MAP_SIZE ((__NR_syscalls + 31) / 32) @@ -83,6 +84,7 @@ struct vdso_data { __u32 icache_log_block_size; /* L1 i-cache log block size */ __s32 wtom_clock_sec; /* Wall to monotonic clock */ __s32 wtom_clock_nsec; + struct timespec stamp_xtime; /* xtime as at tb_orig_stamp */ __u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls */ __u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */ }; @@ -102,6 +104,7 @@ struct vdso_data { __u32 tz_dsttime; /* Type of dst correction 0x5C */ __s32 wtom_clock_sec; /* Wall to monotonic clock */ __s32 wtom_clock_nsec; + struct timespec stamp_xtime; /* xtime as at tb_orig_stamp */ __u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */ __u32 dcache_block_size; /* L1 d-cache block size */ __u32 icache_block_size; /* L1 i-cache block size */ |