kernel.git/arch/x86/kernel/tsc.c, branch linux-2.6.28.y

sched: optimize sched_clock() a bit

2008-11-08T16:05:38Z

sched_clock() uses cycles_2_ns() needlessly - which is an irq-disabling variant of __cycles_2_ns(). Most of the time sched_clock() is called with irqs disabled already. The few places that call it with irqs enabled need to be updated. Signed-off-by: Ingo Molnar

x86: don't use tsc_khz to calculate lpj if notsc is passed

2008-11-04T08:55:26Z

Impact: fix udelay when "notsc" boot parameter is passed With notsc passed on commandline, tsc may not be used for udelays, make sure that we do not use tsc_khz to calculate the lpj value in such cases. Reported-by: Bartlomiej Zolnierkiewicz Signed-off-by: Alok N Kataria Cc: Signed-off-by: Ingo Molnar

x86: use CONFIG_X86_SMP instead of CONFIG_SMP

2008-10-30T21:53:10Z

Impact: fix x86/Voyager boot CONFIG_SMP is used for features which work on *all* x86 boxes. CONFIG_X86_SMP is used for standard PC like x86 boxes (for things like multi core and apics) Signed-off-by: James Bottomley Signed-off-by: Ingo Molnar

Merge branches 'x86/alternatives', 'x86/cleanups', 'x86/commandline', 'x86/crashdump', 'x86/debug', 'x86/defconfig', 'x86/doc', 'x86/exports', 'x86/fpu', 'x86/gart', 'x86/idle', 'x86/mm', 'x86/mtrr', 'x86/nmi-watchdog', 'x86/oprofile', 'x86/paravirt', 'x86/reboot', 'x86/sparse-fixes', 'x86/tsc', 'x86/urgent' and 'x86/vmalloc' into x86-v28-for-linus-phase1

2008-10-06T16:17:07Z

x86, tsc calibration: fix

2008-09-06T21:55:40Z

my brown paperbag day ... Signed-off-by: Ingo Molnar

x86: quick TSC calibration, improve

2008-09-04T21:21:57Z

- make sure the final TSC timestamp is reliable too Signed-off-by: Ingo Molnar

x86: quick TSC calibration

2008-09-04T20:54:50Z

Introduce a fast TSC-calibration method on sane hardware. It only uses 17920 PIT timer ticks to calibrate the TSC, plus 256 ticks on each side to make sure the TSC values were very close to the tick, so the whole calibration takes 15ms. Yet, despite only takign 15ms, we can actually give pretty stringent guarantees of accuracy: - the code requires that we hit each 256-counter block at least 50 times, so the TSC error is basically at *MOST* just a few PIT cycles off in any direction. In practice, it's going to be about one microseconds off (which is how long it takes to read the counter) - so over 17920 PIT cycles, we can pretty much guarantee that the calibration error is less than one half of a percent. My testing bears this out: on my machine, the quick-calibration reports 2934.085kHz, while the slow one reports 2933.415. Yes, the slower calibration is still more precise. For me, the slow calibration is stable to within about one hundreth of a percent, so it's (at a guess) roughly an order-and-a-half of magnitude more precise. The longer you wait, the more precise you can be. However, the nice thing about the fast TSC PIT synchronization is that it's pretty much _guaranteed_ to give that 0.5% precision, and fail gracefully (and very quickly) if it doesn't get it. And it really is fairly simple (even if there's a lot of _details_ there, and I didn't get all of those right ont he first try or even the second ;) The patch says "110 insertions", but 63 of those new lines are actually comments. Signed-off-by: Linus Torvalds Signed-off-by: Ingo Molnar --- arch/x86/kernel/tsc.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 110 insertions(+), 1 deletions(-)

x86: TSC make the calibration loop smarter

2008-09-04T15:35:35Z

The last changes made the calibration loop 250ms long which is far too much. Try to do that more clever. Experiments have shown that using a 10ms delay for the PIT based calibration gives us a good enough value. If we have a reference (HPET/PMTIMER) and the result of the PIT and the reference is close enough, then we can break out of the calibration loop on a match right away and use the reference value. Otherwise we just loop 3 times and decide then, which value to take. One caveat is that for virtualized environments the PIT calibration often does not work at all and I found out that 10us is a bit too short as well for the reference to give a sane result. The solution here is to make the last loop longer when the first two PIT calibrations failed. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

x86: TSC: use one set of reference variables

2008-09-04T15:35:34Z

Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

x86: TSC: separate hpet/pmtimer calculation out

2008-09-04T15:35:33Z

Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar