linux/kernel/time.c, branch v2.6.24

whitespace fixes: time syscalls

2007-10-18T21:37:24Z

Signed-off-by: Daniel Walker Cc: Thomas Gleixner Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Fix discrepancy between VDSO based gettimeofday() and sys_gettimeofday().

2007-10-18T21:37:20Z

On platforms that copy sys_tz into the vdso (currently only x86_64, soon to include powerpc), it is possible for the vdso to get out of sync if a user calls (admittedly unusual) settimeofday(NULL, ptr). This patch adds a hook for architectures that set CONFIG_GENERIC_TIME_VSYSCALL to ensure when sys_tz is updated they can also updatee their copy in the vdso. Signed-off-by: Tony Breeds Cc: Andi Kleen Cc: Tony Luck Acked-by: John Stultz Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Clean up duplicate includes in kernel/

2007-10-17T15:42:48Z

This patch cleans up duplicate includes in kernel/ Signed-off-by: Jesper Juhl Acked-by: Paul E. McKenney Reviewed-by: Satyam Sharma Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

time: introduce xtime_seconds

2007-10-16T17:01:50Z

improve performance of sys_time(). sys_time() returns time in seconds, but it does so by calling do_gettimeofday() and then returning the tv_sec portion of the GTOD time. But the data structure "xtime", which is updated by every timer/scheduler tick, already offers HZ granularity time. the patch improves the sysbench oltp macrobenchmark by 4-5% on an AMD dual-core system: v2.6.23: #threads 1: transactions: 4073 (407.23 per sec.) 2: transactions: 8530 (852.81 per sec.) 3: transactions: 8321 (831.88 per sec.) 4: transactions: 8407 (840.58 per sec.) 5: transactions: 8070 (806.74 per sec.) v2.6.23 + sys_time-speedup.patch: 1: transactions: 4281 (428.09 per sec.) 2: transactions: 8910 (890.85 per sec.) 3: transactions: 8659 (865.79 per sec.) 4: transactions: 8676 (867.34 per sec.) 5: transactions: 8532 (852.91 per sec.) and by 4-5% on an Intel dual-core system too: 2.6.23: 1: transactions: 4560 (455.94 per sec.) 2: transactions: 10094 (1009.30 per sec.) 3: transactions: 9755 (975.36 per sec.) 4: transactions: 9859 (985.78 per sec.) 5: transactions: 9701 (969.72 per sec.) 2.6.23 + sys_time-speedup.patch: 1: transactions: 4779 (477.84 per sec.) 2: transactions: 10103 (1010.14 per sec.) 3: transactions: 10141 (1013.93 per sec.) 4: transactions: 10371 (1036.89 per sec.) 5: transactions: 10178 (1017.50 per sec.) (the more CPUs the system has, the more speedup this patch gives for this particular workload.) Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Linus Torvalds

Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time().

2007-07-25T17:09:20Z

This avoids use of the kernel-internal "xtime" variable directly outside of the actual time-related functions. Instead, use the helper functions that we already have available to us. This doesn't actually change any behaviour, but this will allow us to fix the fact that "xtime" isn't updated very often with CONFIG_NO_HZ (because much of the realtime information is maintained as separate offsets to 'xtime'), which has caused interfaces that use xtime directly to get a time that is out of sync with the real-time clock by up to a third of a second or so. Signed-off-by: John Stultz Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Linus Torvalds

Revert "sys_time() speedup"

2007-07-20T20:32:46Z

This basically reverts commit 4e44f3497d41db4c3b9051c61410dee8ae4fb49c, while waiting for it to be re-done more completely. There are cases of people mixing "time()" with higher-resolution time sources, and we need to take the nanosecond offsets into account. Ingo has a patch that does that, but it's still under some discussion. In the meantime, just revert back to the old simple situation of just doing the whole exact timesource calculations. But rather than using do_gettimeofday(), use the internal nanosecond resolution getnstimeofday(), which at least avoids one unnecessary conversion (since we really don't care about whether the fractional seconds are nanoseconds or microseconds - we'll just throw them away). Signed-off-by: Linus Torvalds

[IA64] remove time interpolator

2007-07-20T18:23:02Z

Remove time_interpolator code (This is generic code, but only user was ia64. It has been superseded by the CONFIG_GENERIC_TIME code). Signed-off-by: Bob Picco Signed-off-by: John Stultz Signed-off-by: Peter Keilty Signed-off-by: Tony Luck

sys_time() speedup

2007-07-16T16:05:48Z

Improve performance of sys_time(). sys_time() returns time in seconds, but it does so by calling do_gettimeofday() and then returning the tv_sec portion of the GTOD time. But the data structure "xtime", which is updated by every timer/scheduler tick, already offers HZ granularity time. The patch improves the sysbench OLTP macrobenchmark significantly: 2.6.22-rc6: #threads 1: transactions: 3733 (373.21 per sec.) 2: transactions: 6676 (667.46 per sec.) 3: transactions: 6957 (695.50 per sec.) 4: transactions: 7055 (705.48 per sec.) 5: transactions: 6596 (659.33 per sec.) 2.6.22-rc6 + sys_time.patch: 1: transactions: 4005 (400.47 per sec.) 2: transactions: 7379 (737.77 per sec.) 3: transactions: 7347 (734.49 per sec.) 4: transactions: 7468 (746.65 per sec.) 5: transactions: 7428 (742.47 per sec.) Mixed API uses of gettimeofday() and time() are guaranteed to be coherent via the use of a at-most-once-per-second slowpath that updates xtime. [akpm@linux-foundation.org: build fixes] Signed-off-by: Ingo Molnar Cc: John Stultz Cc: Thomas Gleixner Cc: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

header cleaning: don't include smp_lock.h when not used

2007-05-08T18:15:07Z

Remove includes of where it is not used/needed. Suggested by Al Viro. Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc, sparc64, and arm (all 59 defconfigs). Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Optimize timespec_trunc()

2007-05-08T18:15:01Z

The first thing done by timespec_trunc() is : if (gran <= jiffies_to_usecs(1) * 1000) This should really be a test against a constant known at compile time. Alas, it isnt. jiffies_to_usec() was unilined so C compiler emits a function call and a multiply to compute : a CONSTANT. mov $0x1,%edi mov %rbx,0xffffffffffffffe8(%rbp) mov %r12,0xfffffffffffffff0(%rbp) mov %edx,%ebx mov %rsi,0xffffffffffffffc8(%rbp) mov %rsi,%r12 callq ffffffff80232010 imul $0x3e8,%eax,%eax cmp %ebx,%eax This patch reorders kernel/time.c a bit so that jiffies_to_usecs() is defined before timespec_trunc() so that compiler now generates : cmp $0x3d0900,%edx (HZ=250 on my machine) This gives a better code (timespec_trunc() becoming a leaf function), and shorter kernel size as well. Signed-off-by: Eric Dumazet Cc: Thomas Gleixner Cc: Ingo Molnar Cc: john stultz Cc: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds