summaryrefslogtreecommitdiffstats
path: root/kernel/time/timekeeping.c
Commit message (Collapse)AuthorAgeFilesLines
* kernel/time/timekeeping.c: cleanupsAdrian Bunk2007-10-171-4/+1
| | | | | | | | | | | | | - remove the no longer required __attribute__((weak)) of xtime_lock - remove the following no longer used EXPORT_SYMBOL's: - xtime - xtime_lock Signed-off-by: Adrian Bunk <bunk@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* time: introduce xtime_secondsIngo Molnar2007-10-161-7/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* timekeeping: Prevent time going backwards on resumeThomas Gleixner2007-09-161-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Timekeeping resume adjusts xtime by adding the slept time in seconds and resets the reference value of the clock source (clock->cycle_last). clock->cycle last is used to calculate the delta between the last xtime update and the readout of the clock source in __get_nsec_offset(). xtime plus the offset is the current time. The resume code ignores the delta which had already elapsed between the last xtime update and the actual time of suspend. If the suspend time is short, then we can see time going backwards on resume. Suspend: offs_s = clock->read() - clock->cycle_last; now = xtime + offs_s; timekeeping_suspend_time = read_rtc(); Resume: sleep_time = read_rtc() - timekeeping_suspend_time; xtime.tv_sec += sleep_time; clock->cycle_last = clock->read(); offs_r = clock->read() - clock->cycle_last; now = xtime + offs_r; if sleep_time_seconds == 0 and offs_r < offs_s, then time goes backwards. Fix this by storing the offset from the last xtime update and add it to xtime during resume, when we reset clock->cycle_last: sleep_time = read_rtc() - timekeeping_suspend_time; xtime.tv_sec += sleep_time; xtime += offs_s; /* Fixup xtime offset at suspend time */ clock->cycle_last = clock->read(); offs_r = clock->read() - clock->cycle_last; now = xtime + offs_r; Thanks to Marcelo for tracking this down on the OLPC and providing the necessary details to analyze the root cause. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <johnstul@us.ibm.com> Cc: Tosatti <marcelo@kvack.org>
* timekeeping: access rtc outside of xtime lockThomas Gleixner2007-09-161-1/+2
| | | | | | | | | | Lockdep complains about the access of rtc in timekeeping_suspend inside the interrupt disabled region of the write locked xtime lock. Move the access outside. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <johnstul@us.ibm.com>
* Cache xtime every call to update_wall_timejohn stultz2007-07-251-3/+23
| | | | | | | | | | | | | | | | | | | | This avoids xtime lag seen with dynticks, because while 'xtime' itself is still not updated often, we keep a 'xtime_cache' variable around that contains the approximate real-time that _is_ updated each time we do a 'update_wall_time()', and is thus never off by more than one tick. IOW, this restores the original semantics for 'xtime' users, as long as you use the proper abstraction functions (ie 'current_kernel_time()' or 'get_seconds()' depending on whether you want a timespec or just the seconds field). [ Updated Patch. As penance for my sins I've also yanked another #ifdef that was added to avoid the xtime lag w/ hrtimers. ] Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time().john stultz2007-07-251-0/+16
| | | | | | | | | | | | | | | | | | 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 <johnstul@us.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Pull ia64-clocksource into release branchTony Luck2007-07-201-4/+0
|\
| * [IA64] remove time interpolatorBob Picco2007-07-201-4/+0
| | | | | | | | | | | | | | | | | | | | | | 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 <bob.picco@hp.com> Signed-off-by: John Stultz <johnstul@us.ibm.com> Signed-off-by: Peter Keilty <peter.keilty@hp.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
* | timekeeping: fixup shadow variable argumentThomas Gleixner2007-07-191-2/+2
|/ | | | | | | | | | clocksource_adjust() has a clock argument, which shadows the file global clock variable. Fix this up. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Introduce boot based timeTomas Janousek2007-07-161-0/+37
| | | | | | | | | | | | | | | | | | | | | | | | | The commits 411187fb05cd11676b0979d9fbf3291db69dbce2 (GTOD: persistent clock support) c1d370e167d66b10bca3b602d3740405469383de (i386: use GTOD persistent clock support) changed the monotonic time so that it no longer jumps after resume, but it's not possible to use it for boot time and process start time calculations then. Also, the uptime no longer increases during suspend. I add a variable to track the wall_to_monotonic changes, a function to get the real boot time and a function to get the boot based time from the monotonic one. [akpm@linux-foundation.org: remove exports, add comment] Signed-off-by: Tomas Janousek <tjanouse@redhat.com> Cc: Tomas Smetana <tsmetana@redhat.com> Cc: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* timekeeping fix patch got mis-appliedThomas Gleixner2007-05-141-0/+2
| | | | | | | | | | | The time keeping code move to kernel/time/timekeeping.c broke the clocksource resume logic patch, which got applied to the old file by a fuzzy application. Fix it up and move the clocksource_resume() call to the appropriate place. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ tssk, tssk, everybody should use --fuzz=0 ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Move timekeeping code to timekeeping.cjohn stultz2007-05-081-0/+476
Move the timekeeping code out of kernel/timer.c and into kernel/time/timekeeping.c. I made no cleanups or other changes in transit. [akpm@linux-foundation.org: build fix] Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
OpenPOWER on IntegriCloud