180 lines
4.3 KiB
C
180 lines
4.3 KiB
C
#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/pm.h>
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struct kmem_cache *task_xstate_cachep;
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int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
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{
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*dst = *src;
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if (src->thread.xstate) {
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dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
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GFP_KERNEL);
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if (!dst->thread.xstate)
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return -ENOMEM;
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WARN_ON((unsigned long)dst->thread.xstate & 15);
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memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
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}
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return 0;
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}
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void free_thread_xstate(struct task_struct *tsk)
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{
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if (tsk->thread.xstate) {
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kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
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tsk->thread.xstate = NULL;
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}
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}
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void free_thread_info(struct thread_info *ti)
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{
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free_thread_xstate(ti->task);
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free_pages((unsigned long)ti, get_order(THREAD_SIZE));
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}
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void arch_task_cache_init(void)
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{
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task_xstate_cachep =
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kmem_cache_create("task_xstate", xstate_size,
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__alignof__(union thread_xstate),
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SLAB_PANIC, NULL);
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}
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static void do_nothing(void *unused)
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{
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}
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/*
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* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
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* pm_idle and update to new pm_idle value. Required while changing pm_idle
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* handler on SMP systems.
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*
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* Caller must have changed pm_idle to the new value before the call. Old
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* pm_idle value will not be used by any CPU after the return of this function.
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*/
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void cpu_idle_wait(void)
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{
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smp_mb();
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/* kick all the CPUs so that they exit out of pm_idle */
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smp_call_function(do_nothing, NULL, 0, 1);
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}
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EXPORT_SYMBOL_GPL(cpu_idle_wait);
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/*
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* This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
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* which can obviate IPI to trigger checking of need_resched.
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* We execute MONITOR against need_resched and enter optimized wait state
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* through MWAIT. Whenever someone changes need_resched, we would be woken
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* up from MWAIT (without an IPI).
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*
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* New with Core Duo processors, MWAIT can take some hints based on CPU
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* capability.
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*/
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void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
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{
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if (!need_resched()) {
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__monitor((void *)¤t_thread_info()->flags, 0, 0);
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smp_mb();
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if (!need_resched())
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__mwait(ax, cx);
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}
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}
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/* Default MONITOR/MWAIT with no hints, used for default C1 state */
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static void mwait_idle(void)
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{
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if (!need_resched()) {
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__monitor((void *)¤t_thread_info()->flags, 0, 0);
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smp_mb();
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if (!need_resched())
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__sti_mwait(0, 0);
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else
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local_irq_enable();
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} else
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local_irq_enable();
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}
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/*
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* On SMP it's slightly faster (but much more power-consuming!)
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* to poll the ->work.need_resched flag instead of waiting for the
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* cross-CPU IPI to arrive. Use this option with caution.
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*/
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static void poll_idle(void)
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{
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local_irq_enable();
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cpu_relax();
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}
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/*
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* mwait selection logic:
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*
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* It depends on the CPU. For AMD CPUs that support MWAIT this is
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* wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
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* then depend on a clock divisor and current Pstate of the core. If
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* all cores of a processor are in halt state (C1) the processor can
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* enter the C1E (C1 enhanced) state. If mwait is used this will never
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* happen.
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*
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* idle=mwait overrides this decision and forces the usage of mwait.
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*/
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static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
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{
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if (force_mwait)
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return 1;
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if (c->x86_vendor == X86_VENDOR_AMD) {
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switch(c->x86) {
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case 0x10:
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case 0x11:
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return 0;
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}
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}
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return 1;
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}
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void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
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{
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static int selected;
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if (selected)
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return;
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#ifdef CONFIG_X86_SMP
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if (pm_idle == poll_idle && smp_num_siblings > 1) {
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printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
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" performance may degrade.\n");
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}
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#endif
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if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
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/*
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* Skip, if setup has overridden idle.
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* One CPU supports mwait => All CPUs supports mwait
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*/
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if (!pm_idle) {
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printk(KERN_INFO "using mwait in idle threads.\n");
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pm_idle = mwait_idle;
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}
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}
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selected = 1;
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}
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static int __init idle_setup(char *str)
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{
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if (!strcmp(str, "poll")) {
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printk("using polling idle threads.\n");
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pm_idle = poll_idle;
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} else if (!strcmp(str, "mwait"))
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force_mwait = 1;
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else
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return -1;
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boot_option_idle_override = 1;
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return 0;
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}
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early_param("idle", idle_setup);
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