Messages in this thread Patch in this message | | | Date | Wed, 20 Dec 2006 06:05:00 -0800 | From | Stephane Eranian <> | Subject | [PATCH] add i386 idle notifier (take 3) |
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Hello,
Here is the latest version of the idle notifier for i386. This patch is against 2.6.20-rc1 (GIT). In this kernel, the idle loop code was modified such that the lowest level idle routines do not have loops anymore (e.g., poll_idle). As such, we do not need to call enter_idle() in all the interrupt handlers.
This patch also duplicates the x86-64 bug fix for a race condition as posted by Venkatesh Pallipadi from Intel.
changelog: - add idle notification mechanism to i386
signed-off-by: stephane eranian <eranian@hpl.hp.com>
diff --exclude=.git -urNp linux-2.6.orig/arch/i386/kernel/apic.c linux-2.6.base/arch/i386/kernel/apic.c --- linux-2.6.orig/arch/i386/kernel/apic.c 2006-12-13 16:22:10.000000000 -0800 +++ linux-2.6.base/arch/i386/kernel/apic.c 2006-12-18 04:51:35.000000000 -0800 @@ -36,6 +36,7 @@ #include <asm/hpet.h> #include <asm/i8253.h> #include <asm/nmi.h> +#include <asm/idle.h> #include <mach_apic.h> #include <mach_apicdef.h> @@ -1255,6 +1256,7 @@ fastcall void smp_apic_timer_interrupt(s * Besides, if we don't timer interrupts ignore the global * interrupt lock, which is the WrongThing (tm) to do. */ + exit_idle(); irq_enter(); smp_local_timer_interrupt(); irq_exit(); @@ -1305,6 +1307,7 @@ fastcall void smp_spurious_interrupt(str { unsigned long v; + exit_idle(); irq_enter(); /* * Check if this really is a spurious interrupt and ACK it @@ -1329,6 +1332,7 @@ fastcall void smp_error_interrupt(struct { unsigned long v, v1; + exit_idle(); irq_enter(); /* First tickle the hardware, only then report what went on. -- REW */ v = apic_read(APIC_ESR); diff --exclude=.git -urNp linux-2.6.orig/arch/i386/kernel/cpu/mcheck/p4.c linux-2.6.base/arch/i386/kernel/cpu/mcheck/p4.c --- linux-2.6.orig/arch/i386/kernel/cpu/mcheck/p4.c 2006-10-17 05:33:35.000000000 -0700 +++ linux-2.6.base/arch/i386/kernel/cpu/mcheck/p4.c 2006-12-18 04:52:37.000000000 -0800 @@ -12,6 +12,7 @@ #include <asm/system.h> #include <asm/msr.h> #include <asm/apic.h> +#include <asm/idle.h> #include <asm/therm_throt.h> @@ -59,6 +60,7 @@ static void (*vendor_thermal_interrupt)( fastcall void smp_thermal_interrupt(struct pt_regs *regs) { + exit_idle(); irq_enter(); vendor_thermal_interrupt(regs); irq_exit(); diff --exclude=.git -urNp linux-2.6.orig/arch/i386/kernel/irq.c linux-2.6.base/arch/i386/kernel/irq.c --- linux-2.6.orig/arch/i386/kernel/irq.c 2006-10-26 14:12:56.000000000 -0700 +++ linux-2.6.base/arch/i386/kernel/irq.c 2006-12-18 04:52:42.000000000 -0800 @@ -19,6 +19,8 @@ #include <linux/cpu.h> #include <linux/delay.h> +#include <asm/idle.h> + DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp; EXPORT_PER_CPU_SYMBOL(irq_stat); @@ -61,6 +63,7 @@ fastcall unsigned int do_IRQ(struct pt_r union irq_ctx *curctx, *irqctx; u32 *isp; #endif + exit_idle(); if (unlikely((unsigned)irq >= NR_IRQS)) { printk(KERN_EMERG "%s: cannot handle IRQ %d\n", diff --exclude=.git -urNp linux-2.6.orig/arch/i386/kernel/process.c linux-2.6.base/arch/i386/kernel/process.c --- linux-2.6.orig/arch/i386/kernel/process.c 2006-12-13 16:22:10.000000000 -0800 +++ linux-2.6.base/arch/i386/kernel/process.c 2006-12-18 04:54:36.000000000 -0800 @@ -48,6 +48,7 @@ #include <asm/i387.h> #include <asm/desc.h> #include <asm/vm86.h> +#include <asm/idle.h> #ifdef CONFIG_MATH_EMULATION #include <asm/math_emu.h> #endif @@ -80,6 +81,43 @@ void (*pm_idle)(void); EXPORT_SYMBOL(pm_idle); static DEFINE_PER_CPU(unsigned int, cpu_idle_state); +static ATOMIC_NOTIFIER_HEAD(idle_notifier); + +void idle_notifier_register(struct notifier_block *n) +{ + atomic_notifier_chain_register(&idle_notifier, n); +} +EXPORT_SYMBOL_GPL(idle_notifier_register); + +void idle_notifier_unregister(struct notifier_block *n) +{ + atomic_notifier_chain_unregister(&idle_notifier, n); +} +EXPORT_SYMBOL(idle_notifier_unregister); + +static DEFINE_PER_CPU(volatile unsigned long, idle_state); + +void enter_idle(void) +{ + __get_cpu_var(idle_state) = 1; + atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL); +} + +static void __exit_idle() +{ + /* needs to be atomic w.r.t. interrupts, not against other CPUs */ + if (__test_and_clear_bit(0, &__get_cpu_var(idle_state)) == 0) + return; + atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL); +} + +void exit_idle(void) +{ + if (current->pid) + return; + __exit_idle(); +} + void disable_hlt(void) { hlt_counter++; @@ -125,6 +163,7 @@ EXPORT_SYMBOL(default_idle); */ static void poll_idle (void) { + local_irq_enable(); cpu_relax(); } @@ -184,7 +223,16 @@ void cpu_idle(void) play_dead(); __get_cpu_var(irq_stat).idle_timestamp = jiffies; + + /* + * Idle routines should keep interrupts disabled + * from here on, until they go to idle. + * Otherwise, idle callbacks can misfire. + */ + local_irq_disable(); + enter_idle(); idle(); + __exit_idle(); } preempt_enable_no_resched(); schedule(); @@ -238,7 +286,11 @@ void mwait_idle_with_hints(unsigned long __monitor((void *)¤t_thread_info()->flags, 0, 0); smp_mb(); if (!need_resched()) - __mwait(eax, ecx); + __sti_mwait(eax, ecx); + else + local_irq_enable(); + } else { + local_irq_enable(); } } diff --exclude=.git -urNp linux-2.6.orig/arch/i386/kernel/smp.c linux-2.6.base/arch/i386/kernel/smp.c --- linux-2.6.orig/arch/i386/kernel/smp.c 2006-12-13 16:22:10.000000000 -0800 +++ linux-2.6.base/arch/i386/kernel/smp.c 2006-12-18 04:56:30.000000000 -0800 @@ -23,6 +23,7 @@ #include <asm/mtrr.h> #include <asm/tlbflush.h> +#include <asm/idle.h> #include <mach_apic.h> /* @@ -624,6 +625,7 @@ fastcall void smp_call_function_interrup /* * At this point the info structure may be out of scope unless wait==1 */ + exit_idle(); irq_enter(); (*func)(info); irq_exit(); diff --exclude=.git -urNp linux-2.6.orig/include/asm-i386/idle.h linux-2.6.base/include/asm-i386/idle.h --- linux-2.6.orig/include/asm-i386/idle.h 1969-12-31 16:00:00.000000000 -0800 +++ linux-2.6.base/include/asm-i386/idle.h 2006-12-18 04:49:27.000000000 -0800 @@ -0,0 +1,14 @@ +#ifndef _ASM_I386_IDLE_H +#define _ASM_I386_IDLE_H 1 + +#define IDLE_START 1 +#define IDLE_END 2 + +struct notifier_block; +void idle_notifier_register(struct notifier_block *n); +void idle_notifier_unregister(struct notifier_block *n); + +void exit_idle(void); +void enter_idle(void); + +#endif diff --exclude=.git -urNp linux-2.6.orig/include/asm-i386/processor.h linux-2.6.base/include/asm-i386/processor.h --- linux-2.6.orig/include/asm-i386/processor.h 2006-12-13 16:22:22.000000000 -0800 +++ linux-2.6.base/include/asm-i386/processor.h 2006-12-13 16:38:11.000000000 -0800 @@ -257,6 +257,14 @@ static inline void __mwait(unsigned long : :"a" (eax), "c" (ecx)); } +static inline void __sti_mwait(unsigned long eax, unsigned long ecx) +{ + /* "mwait %eax,%ecx;" */ + asm volatile( + "sti; .byte 0x0f,0x01,0xc9;" + : :"a" (eax), "c" (ecx)); +} + extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx); /* from system description table in BIOS. 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