linux/kernel/sched_clock.c, branch v2.6.32

sched_clock: Fix atomicity/continuity bug by using cmpxchg64()

2009-09-30T20:56:10Z

Commit def0a9b2573 (sched_clock: Make it NMI safe) assumed cmpxchg() of 64bit values was available on X86_32. That is not so - and causes some subtle scheduler misbehavior due to incorrect timestamps off to up by ~4 seconds. Two symptoms are known right now: - interactivity problems seen by Arjan: up to 600 msecs latencies instead of the expected 20-40 msecs. These latencies are very visible on the desktop. - incorrect CPU stats: occasionally too high percentages in 'top', and crazy CPU usage stats. Reported-by: Martin Schwidefsky Signed-off-by: Eric Dumazet Signed-off-by: Arjan van de Ven Acked-by: Linus Torvalds Cc: John Stultz Cc: Peter Zijlstra LKML-Reference: <20090930170754.0886ff2e@infradead.org> Signed-off-by: Ingo Molnar

sched_clock: Make it NMI safe

2009-09-18T18:47:30Z

Arjan complained about the suckyness of TSC on modern machines, and asked if we could do something about that for PERF_SAMPLE_TIME. Make cpu_clock() NMI safe by removing the spinlock and using cmpxchg. This also makes it smaller and more robust. Affects architectures that use HAVE_UNSTABLE_SCHED_CLOCK, i.e. IA64 and x86. Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar

sched: Fix fallback sched_clock()'s offset when using jiffies

2009-05-09T08:08:19Z

Account for the initial offset to the jiffy count. [ Impact: fix printk timestamps on architectures using fallback sched_clock() ] Signed-off-by: Ron Lee Cc: Andrew Morton Signed-off-by: Ingo Molnar

Merge branch 'tracing/core-v2' into tracing-for-linus

2009-04-01T22:49:02Z

Conflicts: include/linux/slub_def.h lib/Kconfig.debug mm/slob.c mm/slub.c

Merge branch 'sched/clock' into tracing/ftrace

2009-02-27T07:35:19Z

Conflicts: kernel/sched_clock.c

sched_clock: cleanups

2009-02-26T20:56:07Z

- remove superfluous checks in __update_sched_clock() - skip sched_clock_tick() for sched_clock_stable - reinstate the simple !HAVE_UNSTABLE_SCHED_CLOCK code to please the bloatwatch Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar

sched: allow architectures to specify sched_clock_stable

2009-02-26T20:20:22Z

Allow CONFIG_HAVE_UNSTABLE_SCHED_CLOCK architectures to still specify that their sched_clock() implementation is reliable. This will be used by x86 to switch on a faster sched_clock_cpu() implementation on certain CPU types. Signed-off-by: Ingo Molnar

sched: sched_clock() improvement: use in_nmi()

2009-02-26T17:44:05Z

make sure we dont execute more complex sched_clock() code in NMI context. Acked-by: Peter Zijlstra Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar

sched_clock: prevent scd->clock from moving backwards, take #2

2008-12-31T08:53:21Z

Redo: 5b7dba4: sched_clock: prevent scd->clock from moving backwards which had to be reverted due to s2ram hangs: ca7e716: Revert "sched_clock: prevent scd->clock from moving backwards" ... this time with resume restoring GTOD later in the sequence taken into account as well. The "timekeeping_suspended" flag is not very nice but we cannot call into GTOD before it has been properly resumed and the scheduler will run very early in the resume sequence. Cc: Signed-off-by: Ingo Molnar

Revert "sched_clock: prevent scd->clock from moving backwards"

2008-12-15T00:23:17Z

This reverts commit 5b7dba4ff834259a5623e03a565748704a8fe449, which caused a regression in hibernate, reported by and bisected by Fabio Comolli. This revert fixes http://bugzilla.kernel.org/show_bug.cgi?id=12155 http://bugzilla.kernel.org/show_bug.cgi?id=12149 Bisected-by: Fabio Comolli Requested-by: Rafael J. Wysocki Acked-by: Dave Kleikamp Cc: Peter Zijlstra Cc: Ingo Molnar Signed-off-by: Linus Torvalds