[PATCH] x86_64: Remove the broadcast options that were added for cpuhotplug (37a47e65) · Commits · e / devices / android_kernel_teracube_2e

arch/x86_64/kernel/genapic_flat.c

+2 −86

Original line number	Diff line number	Diff line
		@@ -7,8 +7,6 @@
		* Hacked for x86-64 by James Cleverdon from i386 architecture code by
		* Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
		* James Cleverdon.
		* Ashok Raj <ashok.raj@intel.com>
		* Removed IPI broadcast shortcut to support CPU hotplug
		*/
		#include <linux/config.h>
		#include <linux/threads.h>
		@@ -20,47 +18,6 @@
		#include <asm/smp.h>
		#include <asm/ipi.h>

		/*
		* The following permit choosing broadcast IPI shortcut v.s sending IPI only
		* to online cpus via the send_IPI_mask varient.
		* The mask version is my preferred option, since it eliminates a lot of
		* other extra code that would need to be written to cleanup intrs sent
		* to a CPU while offline.
		*
		* Sending broadcast introduces lots of trouble in CPU hotplug situations.
		* These IPI's are delivered to cpu's irrespective of their offline status
		* and could pickup stale intr data when these CPUS are turned online.
		*
		* Not using broadcast is a cleaner approach IMO, but Andi Kleen disagrees with
		* the idea of not using broadcast IPI's anymore. Hence the run time check
		* is introduced, on his request so we can choose an alternate mechanism.
		*
		* Initial wacky performance tests that collect cycle counts show
		* no increase in using mask v.s broadcast version. In fact they seem
		* identical in terms of cycle counts.
		*
		* if we need to use broadcast, we need to do the following.
		*
		* cli;
		* hold call_lock;
		* clear any pending IPI, just ack and clear all pending intr
		* set cpu_online_map;
		* release call_lock;
		* sti;
		*
		* The complicated dummy irq processing shown above is not required if
		* we didnt sent IPI's to wrong CPU's in the first place.
		*
		* - Ashok Raj <ashok.raj@intel.com>
		*/
		#ifdef CONFIG_HOTPLUG_CPU
		#define DEFAULT_SEND_IPI (1)
		#else
		#define DEFAULT_SEND_IPI (0)
		#endif

		static int no_broadcast=DEFAULT_SEND_IPI;

		static cpumask_t flat_target_cpus(void)
		{
		return cpu_online_map;
		@@ -119,37 +76,15 @@ static void flat_send_IPI_mask(cpumask_t cpumask, int vector)
		local_irq_restore(flags);
		}

		static inline void __local_flat_send_IPI_allbutself(int vector)
		{
		if (no_broadcast) {
		cpumask_t mask = cpu_online_map;
		int this_cpu = get_cpu();

		cpu_clear(this_cpu, mask);
		flat_send_IPI_mask(mask, vector);
		put_cpu();
		}
		else
		__send_IPI_shortcut(APIC_DEST_ALLBUT, vector, APIC_DEST_LOGICAL);
		}

		static inline void __local_flat_send_IPI_all(int vector)
		{
		if (no_broadcast)
		flat_send_IPI_mask(cpu_online_map, vector);
		else
		__send_IPI_shortcut(APIC_DEST_ALLINC, vector, APIC_DEST_LOGICAL);
		}

		static void flat_send_IPI_allbutself(int vector)
		{
		if (((num_online_cpus()) - 1) >= 1)
		__local_flat_send_IPI_allbutself(vector);
		__send_IPI_shortcut(APIC_DEST_ALLBUT, vector,APIC_DEST_LOGICAL);
		}

		static void flat_send_IPI_all(int vector)
		{
		__local_flat_send_IPI_all(vector);
		__send_IPI_shortcut(APIC_DEST_ALLINC, vector, APIC_DEST_LOGICAL);
		}

		static int flat_apic_id_registered(void)
		@@ -170,16 +105,6 @@ static unsigned int phys_pkg_id(int index_msb)
		return ((ebx >> 24) & 0xFF) >> index_msb;
		}

		static __init int no_ipi_broadcast(char *str)
		{
		get_option(&str, &no_broadcast);
		printk ("Using %s mode\n", no_broadcast ? "No IPI Broadcast" :
		"IPI Broadcast");
		return 1;
		}

		__setup("no_ipi_broadcast", no_ipi_broadcast);

		struct genapic apic_flat = {
		.name = "flat",
		.int_delivery_mode = dest_LowestPrio,
		@@ -194,12 +119,3 @@ struct genapic apic_flat = {
		.cpu_mask_to_apicid = flat_cpu_mask_to_apicid,
		.phys_pkg_id = phys_pkg_id,
		};

		static int __init print_ipi_mode(void)
		{
		printk ("Using IPI %s mode\n", no_broadcast ? "No-Shortcut" :
		"Shortcut");
		return 0;
		}

		late_initcall(print_ipi_mode);