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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-06 19:08:14 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-06 19:08:14 (GMT) |
commit | d7a5a18190d6f523b5d795bfd73f83cf13a3a383 (patch) | |
tree | a7ec0b814d18c78b42403afae048346f45f82adc /arch | |
parent | 4f00b901d4233a78e6ca4d44c8c6fc5d38a3ee9e (diff) | |
parent | a8760eca6cf60ed303ad494ef45901f63165d2c8 (diff) | |
download | linux-fsl-qoriq-d7a5a18190d6f523b5d795bfd73f83cf13a3a383.tar.xz |
Merge branch 'x86-tsc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-tsc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Check tsc available/disabled in the delayed init function
x86: Improve TSC calibration using a delayed workqueue
x86: Make tsc=reliable override boot time stability checks
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/tsc.c | 96 |
1 files changed, 91 insertions, 5 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 0c40d8b..356a0d4 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -872,6 +872,9 @@ __cpuinit int unsynchronized_tsc(void) if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) return 0; + + if (tsc_clocksource_reliable) + return 0; /* * Intel systems are normally all synchronized. * Exceptions must mark TSC as unstable: @@ -879,14 +882,92 @@ __cpuinit int unsynchronized_tsc(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { /* assume multi socket systems are not synchronized: */ if (num_possible_cpus() > 1) - tsc_unstable = 1; + return 1; } - return tsc_unstable; + return 0; +} + + +static void tsc_refine_calibration_work(struct work_struct *work); +static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work); +/** + * tsc_refine_calibration_work - Further refine tsc freq calibration + * @work - ignored. + * + * This functions uses delayed work over a period of a + * second to further refine the TSC freq value. Since this is + * timer based, instead of loop based, we don't block the boot + * process while this longer calibration is done. + * + * If there are any calibration anomolies (too many SMIs, etc), + * or the refined calibration is off by 1% of the fast early + * calibration, we throw out the new calibration and use the + * early calibration. + */ +static void tsc_refine_calibration_work(struct work_struct *work) +{ + static u64 tsc_start = -1, ref_start; + static int hpet; + u64 tsc_stop, ref_stop, delta; + unsigned long freq; + + /* Don't bother refining TSC on unstable systems */ + if (check_tsc_unstable()) + goto out; + + /* + * Since the work is started early in boot, we may be + * delayed the first time we expire. So set the workqueue + * again once we know timers are working. + */ + if (tsc_start == -1) { + /* + * Only set hpet once, to avoid mixing hardware + * if the hpet becomes enabled later. + */ + hpet = is_hpet_enabled(); + schedule_delayed_work(&tsc_irqwork, HZ); + tsc_start = tsc_read_refs(&ref_start, hpet); + return; + } + + tsc_stop = tsc_read_refs(&ref_stop, hpet); + + /* hpet or pmtimer available ? */ + if (!hpet && !ref_start && !ref_stop) + goto out; + + /* Check, whether the sampling was disturbed by an SMI */ + if (tsc_start == ULLONG_MAX || tsc_stop == ULLONG_MAX) + goto out; + + delta = tsc_stop - tsc_start; + delta *= 1000000LL; + if (hpet) + freq = calc_hpet_ref(delta, ref_start, ref_stop); + else + freq = calc_pmtimer_ref(delta, ref_start, ref_stop); + + /* Make sure we're within 1% */ + if (abs(tsc_khz - freq) > tsc_khz/100) + goto out; + + tsc_khz = freq; + printk(KERN_INFO "Refined TSC clocksource calibration: " + "%lu.%03lu MHz.\n", (unsigned long)tsc_khz / 1000, + (unsigned long)tsc_khz % 1000); + +out: + clocksource_register_khz(&clocksource_tsc, tsc_khz); } -static void __init init_tsc_clocksource(void) + +static int __init init_tsc_clocksource(void) { + if (!cpu_has_tsc || tsc_disabled > 0) + return 0; + if (tsc_clocksource_reliable) clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY; /* lower the rating if we already know its unstable: */ @@ -894,8 +975,14 @@ static void __init init_tsc_clocksource(void) clocksource_tsc.rating = 0; clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS; } - clocksource_register_khz(&clocksource_tsc, tsc_khz); + schedule_delayed_work(&tsc_irqwork, 0); + return 0; } +/* + * We use device_initcall here, to ensure we run after the hpet + * is fully initialized, which may occur at fs_initcall time. + */ +device_initcall(init_tsc_clocksource); void __init tsc_init(void) { @@ -949,6 +1036,5 @@ void __init tsc_init(void) mark_tsc_unstable("TSCs unsynchronized"); check_system_tsc_reliable(); - init_tsc_clocksource(); } |