Attachment 281661 Details for Bug 416141 – idle=poll feature straight from xen-unstable

idle=poll feature straight from xen-unstable

linux-2.6-xen-idle-poll.patch (text/x-patch), 4.09 KB, created by Markus Armbruster on 2007-12-07 21:53:51 UTC

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Creator: Markus Armbruster

Created: 2007-12-07 21:53:51 UTC

Size: 4.09 KB

patch

obsolete

>xen-unstable.hg changesets trivially rediffed:
>13213:bf25488db8eb
>13217:338ceb7b1f09
>
>diff -rupN kernel-2.6.18/linux-2.6.18.noarch/arch/i386/kernel/process-xen.c kernel-2.6.18-patched/linux-2.6.18.noarch/arch/i386/kernel/process-xen.c
>--- a/arch/i386/kernel/process-xen.c	2007-06-06 00:07:28.000000000 +0200
>+++ b/arch/i386/kernel/process-xen.c	2007-06-05 20:35:08.000000000 +0200
>@@ -96,8 +96,24 @@ void enable_hlt(void)
> 
> EXPORT_SYMBOL(enable_hlt);
> 
>-/* XXX XEN doesn't use default_idle(), poll_idle(). Use xen_idle() instead. */
>-void xen_idle(void)
>+/*
>+ * On SMP it's slightly faster (but much more power-consuming!)
>+ * to poll the ->work.need_resched flag instead of waiting for the
>+ * cross-CPU IPI to arrive. Use this option with caution.
>+ */
>+static void poll_idle(void)
>+{
>+	local_irq_enable();
>+
>+	asm volatile(
>+		"2:"
>+		"testl %0, %1;"
>+		"rep; nop;"
>+		"je 2b;"
>+		: : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
>+}
>+
>+static void xen_idle(void)
> {
> 	local_irq_disable();
> 
>@@ -148,17 +164,22 @@ void cpu_idle(void)
> 	/* endless idle loop with no priority at all */
> 	while (1) {
> 		while (!need_resched()) {
>+			void (*idle)(void);
> 
> 			if (__get_cpu_var(cpu_idle_state))
> 				__get_cpu_var(cpu_idle_state) = 0;
> 
> 			rmb();
>+			idle = pm_idle;
>+
>+			if (!idle)
>+				idle = xen_idle;
> 
> 			if (cpu_is_offline(cpu))
> 				play_dead();
> 
> 			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
>-			xen_idle();
>+			idle();
> 		}
> 		preempt_enable_no_resched();
> 		schedule();
>@@ -194,9 +215,22 @@ void cpu_idle_wait(void)
> }
> EXPORT_SYMBOL_GPL(cpu_idle_wait);
> 
>-/* XXX XEN doesn't use mwait_idle(), select_idle_routine(), idle_setup(). */
>-/* Always use xen_idle() instead. */
>-void __devinit select_idle_routine(const struct cpuinfo_x86 *c) {}
>+void __devinit select_idle_routine(const struct cpuinfo_x86 *c)
>+{
>+}
>+
>+static int __init idle_setup (char *str)
>+{
>+	if (!strncmp(str, "poll", 4)) {
>+		printk("using polling idle threads.\n");
>+		pm_idle = poll_idle;
>+	}
>+
>+	boot_option_idle_override = 1;
>+	return 1;
>+}
>+
>+__setup("idle=", idle_setup);
> 
> void show_regs(struct pt_regs * regs)
> {
>diff -rupN kernel-2.6.18/linux-2.6.18.noarch/arch/x86_64/kernel/process-xen.c kernel-2.6.18-patched/linux-2.6.18.noarch/arch/x86_64/kernel/process-xen.c
>--- a/arch/x86_64/kernel/process-xen.c	2007-06-06 00:07:33.000000000 +0200
>+++ b/arch/x86_64/kernel/process-xen.c	2007-06-05 20:35:08.000000000 +0200
>@@ -111,8 +111,26 @@ void exit_idle(void)
> 	__exit_idle();
> }
> 
>-/* XXX XEN doesn't use default_idle(), poll_idle(). Use xen_idle() instead. */
>-void xen_idle(void)
>+/*
>+ * On SMP it's slightly faster (but much more power-consuming!)
>+ * to poll the ->need_resched flag instead of waiting for the
>+ * cross-CPU IPI to arrive. Use this option with caution.
>+ */
>+static void poll_idle(void)
>+{
>+	local_irq_enable();
>+
>+	asm volatile(
>+		"2:"
>+		"testl %0,%1;"
>+		"rep; nop;"
>+		"je 2b;"
>+		: :
>+		"i" (_TIF_NEED_RESCHED),
>+		"m" (current_thread_info()->flags));
>+}
>+
>+static void xen_idle(void)
> {
> 	local_irq_disable();
> 
>@@ -155,14 +173,18 @@ void cpu_idle (void)
> 	/* endless idle loop with no priority at all */
> 	while (1) {
> 		while (!need_resched()) {
>+			void (*idle)(void);
>+
> 			if (__get_cpu_var(cpu_idle_state))
> 				__get_cpu_var(cpu_idle_state) = 0;
> 			rmb();
>-			
>+			idle = pm_idle;
>+			if (!idle)
>+				idle = xen_idle;
> 			if (cpu_is_offline(smp_processor_id()))
> 				play_dead();
> 			enter_idle();
>-			xen_idle();
>+			idle();
> 			__exit_idle();
> 		}
> 
>@@ -201,9 +223,22 @@ void cpu_idle_wait(void)
> }
> EXPORT_SYMBOL_GPL(cpu_idle_wait);
> 
>-/* XXX XEN doesn't use mwait_idle(), select_idle_routine(), idle_setup(). */
>-/* Always use xen_idle() instead. */
>-void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) {}
>+void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) 
>+{
>+}
>+
>+static int __init idle_setup (char *str)
>+{
>+	if (!strncmp(str, "poll", 4)) {
>+		printk("using polling idle threads.\n");
>+		pm_idle = poll_idle;
>+	}
>+
>+	boot_option_idle_override = 1;
>+	return 1;
>+}
>+
>+__setup("idle=", idle_setup);
> 
> /* Prints also some state that isn't saved in the pt_regs */ 
> void __show_regs(struct pt_regs * regs)

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Attachments on bug 416141: 281661