From 597bc5c00b666fe123abb0af64f6e86f7ab72a90 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Mon, 27 Oct 2008 23:56:03 +0000 Subject: 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 --- arch/powerpc/include/asm/vdso_datapage.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/powerpc/include/asm/vdso_datapage.h') 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 +#include #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 */ -- cgit v1.2.3-70-g09d2