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[IA64] Add arch/ia64/kernel/time.c to spare tree for steal time accounting
Signed-off-by: Atsushi SAKAI <sakaia@jp.fujitsu.com>
This commit is contained in:
awilliam@xenbuild2.aw committed
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/*
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* linux/arch/ia64/kernel/time.c
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*
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* Copyright (C) 1998-2003 Hewlett-Packard Co
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* Stephane Eranian <eranian@hpl.hp.com>
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* David Mosberger <davidm@hpl.hp.com>
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* Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
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* Copyright (C) 1999-2000 VA Linux Systems
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* Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
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*/
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#include <linux/cpu.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/profile.h>
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#include <linux/sched.h>
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#include <linux/time.h>
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#include <linux/interrupt.h>
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#include <linux/efi.h>
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#include <linux/profile.h>
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#include <linux/timex.h>
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#include <asm/machvec.h>
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#include <asm/delay.h>
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#include <asm/hw_irq.h>
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#include <asm/ptrace.h>
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#include <asm/sal.h>
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#include <asm/sections.h>
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#include <asm/system.h>
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extern unsigned long wall_jiffies;
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volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
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#ifdef CONFIG_IA64_DEBUG_IRQ
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unsigned long last_cli_ip;
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EXPORT_SYMBOL(last_cli_ip);
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#endif
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static struct time_interpolator itc_interpolator = {
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.shift = 16,
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.mask = 0xffffffffffffffffLL,
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.source = TIME_SOURCE_CPU
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};
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static irqreturn_t
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timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
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{
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unsigned long new_itm;
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if (unlikely(cpu_is_offline(smp_processor_id()))) {
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return IRQ_HANDLED;
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}
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platform_timer_interrupt(irq, dev_id, regs);
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new_itm = local_cpu_data->itm_next;
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if (!time_after(ia64_get_itc(), new_itm))
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printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
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ia64_get_itc(), new_itm);
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profile_tick(CPU_PROFILING, regs);
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while (1) {
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update_process_times(user_mode(regs));
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new_itm += local_cpu_data->itm_delta;
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if (smp_processor_id() == time_keeper_id) {
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/*
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* Here we are in the timer irq handler. We have irqs locally
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* disabled, but we don't know if the timer_bh is running on
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* another CPU. We need to avoid to SMP race by acquiring the
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* xtime_lock.
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*/
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write_seqlock(&xtime_lock);
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do_timer(regs);
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local_cpu_data->itm_next = new_itm;
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write_sequnlock(&xtime_lock);
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} else
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local_cpu_data->itm_next = new_itm;
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if (time_after(new_itm, ia64_get_itc()))
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break;
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}
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do {
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/*
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* If we're too close to the next clock tick for
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* comfort, we increase the safety margin by
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* intentionally dropping the next tick(s). We do NOT
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* update itm.next because that would force us to call
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* do_timer() which in turn would let our clock run
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* too fast (with the potentially devastating effect
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* of losing monotony of time).
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*/
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while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
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new_itm += local_cpu_data->itm_delta;
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ia64_set_itm(new_itm);
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/* double check, in case we got hit by a (slow) PMI: */
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} while (time_after_eq(ia64_get_itc(), new_itm));
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return IRQ_HANDLED;
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}
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/*
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* Encapsulate access to the itm structure for SMP.
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*/
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void
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ia64_cpu_local_tick (void)
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{
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int cpu = smp_processor_id();
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unsigned long shift = 0, delta;
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/* arrange for the cycle counter to generate a timer interrupt: */
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ia64_set_itv(IA64_TIMER_VECTOR);
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delta = local_cpu_data->itm_delta;
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/*
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* Stagger the timer tick for each CPU so they don't occur all at (almost) the
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* same time:
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*/
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if (cpu) {
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unsigned long hi = 1UL << ia64_fls(cpu);
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shift = (2*(cpu - hi) + 1) * delta/hi/2;
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}
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local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
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ia64_set_itm(local_cpu_data->itm_next);
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}
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static int nojitter;
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static int __init nojitter_setup(char *str)
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{
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nojitter = 1;
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printk("Jitter checking for ITC timers disabled\n");
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return 1;
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}
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__setup("nojitter", nojitter_setup);
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void __devinit
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ia64_init_itm (void)
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{
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unsigned long platform_base_freq, itc_freq;
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struct pal_freq_ratio itc_ratio, proc_ratio;
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long status, platform_base_drift, itc_drift;
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/*
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* According to SAL v2.6, we need to use a SAL call to determine the platform base
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* frequency and then a PAL call to determine the frequency ratio between the ITC
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* and the base frequency.
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*/
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status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
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&platform_base_freq, &platform_base_drift);
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if (status != 0) {
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printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
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} else {
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status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
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if (status != 0)
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printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
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}
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if (status != 0) {
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/* invent "random" values */
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printk(KERN_ERR
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"SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
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platform_base_freq = 100000000;
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platform_base_drift = -1; /* no drift info */
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itc_ratio.num = 3;
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itc_ratio.den = 1;
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}
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if (platform_base_freq < 40000000) {
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printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
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platform_base_freq);
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platform_base_freq = 75000000;
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platform_base_drift = -1;
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}
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if (!proc_ratio.den)
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proc_ratio.den = 1; /* avoid division by zero */
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if (!itc_ratio.den)
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itc_ratio.den = 1; /* avoid division by zero */
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itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
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local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
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printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
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"ITC freq=%lu.%03luMHz", smp_processor_id(),
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platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
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itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
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if (platform_base_drift != -1) {
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itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
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printk("+/-%ldppm\n", itc_drift);
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} else {
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itc_drift = -1;
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printk("\n");
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}
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local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
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local_cpu_data->itc_freq = itc_freq;
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local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
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local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
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+ itc_freq/2)/itc_freq;
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if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
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itc_interpolator.frequency = local_cpu_data->itc_freq;
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itc_interpolator.drift = itc_drift;
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#ifdef CONFIG_SMP
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/* On IA64 in an SMP configuration ITCs are never accurately synchronized.
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* Jitter compensation requires a cmpxchg which may limit
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* the scalability of the syscalls for retrieving time.
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* The ITC synchronization is usually successful to within a few
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* ITC ticks but this is not a sure thing. If you need to improve
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* timer performance in SMP situations then boot the kernel with the
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* "nojitter" option. However, doing so may result in time fluctuating (maybe
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* even going backward) if the ITC offsets between the individual CPUs
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* are too large.
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*/
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if (!nojitter) itc_interpolator.jitter = 1;
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#endif
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register_time_interpolator(&itc_interpolator);
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}
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/* Setup the CPU local timer tick */
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ia64_cpu_local_tick();
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}
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static struct irqaction timer_irqaction = {
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.handler = timer_interrupt,
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.flags = IRQF_DISABLED,
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.name = "timer"
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};
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void __devinit ia64_disable_timer(void)
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{
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ia64_set_itv(1 << 16);
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}
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void __init
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time_init (void)
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{
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register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
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efi_gettimeofday(&xtime);
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ia64_init_itm();
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/*
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* Initialize wall_to_monotonic such that adding it to xtime will yield zero, the
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* tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC).
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*/
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set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
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}
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/*
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* Generic udelay assumes that if preemption is allowed and the thread
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* migrates to another CPU, that the ITC values are synchronized across
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* all CPUs.
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*/
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static void
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ia64_itc_udelay (unsigned long usecs)
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{
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unsigned long start = ia64_get_itc();
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unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
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while (time_before(ia64_get_itc(), end))
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cpu_relax();
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}
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void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
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void
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udelay (unsigned long usecs)
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{
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(*ia64_udelay)(usecs);
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}
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EXPORT_SYMBOL(udelay);
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static unsigned long long ia64_itc_printk_clock(void)
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{
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if (ia64_get_kr(IA64_KR_PER_CPU_DATA))
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return sched_clock();
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return 0;
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}
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static unsigned long long ia64_default_printk_clock(void)
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{
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return (unsigned long long)(jiffies_64 - INITIAL_JIFFIES) *
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(1000000000/HZ);
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}
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unsigned long long (*ia64_printk_clock)(void) = &ia64_default_printk_clock;
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unsigned long long printk_clock(void)
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{
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return ia64_printk_clock();
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}
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void __init
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ia64_setup_printk_clock(void)
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{
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if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT))
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ia64_printk_clock = ia64_itc_printk_clock;
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}
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