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x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume
During suspend, we disable all the non boot cpus. And during resume we bring them all back again. So no need to do alternatives_smp_switch() in between. On my core 2 based laptop, this speeds up the suspend path by 15msec and the resume path by 5 msec (suspend/resume speed up differences can be attributed to the different P-states that the cpu is in during suspend/resume). Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <1290557500.4946.8.camel@sbsiddha-MOBL3.sc.intel.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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@ -66,6 +66,7 @@ extern void alternatives_smp_module_add(struct module *mod, char *name,
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extern void alternatives_smp_module_del(struct module *mod);
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extern void alternatives_smp_switch(int smp);
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extern int alternatives_text_reserved(void *start, void *end);
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extern bool skip_smp_alternatives;
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#else
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static inline void alternatives_smp_module_add(struct module *mod, char *name,
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void *locks, void *locks_end,
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@ -353,6 +353,7 @@ void __init_or_module alternatives_smp_module_del(struct module *mod)
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mutex_unlock(&smp_alt);
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}
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bool skip_smp_alternatives;
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void alternatives_smp_switch(int smp)
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{
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struct smp_alt_module *mod;
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@ -368,7 +369,7 @@ void alternatives_smp_switch(int smp)
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printk("lockdep: fixing up alternatives.\n");
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#endif
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if (noreplace_smp || smp_alt_once)
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if (noreplace_smp || smp_alt_once || skip_smp_alternatives)
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return;
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BUG_ON(!smp && (num_online_cpus() > 1));
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@ -1166,6 +1166,20 @@ out:
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preempt_enable();
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}
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void arch_disable_nonboot_cpus_begin(void)
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{
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/*
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* Avoid the smp alternatives switch during the disable_nonboot_cpus().
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* In the suspend path, we will be back in the SMP mode shortly anyways.
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*/
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skip_smp_alternatives = true;
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}
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void arch_disable_nonboot_cpus_end(void)
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{
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skip_smp_alternatives = false;
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}
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void arch_enable_nonboot_cpus_begin(void)
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{
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set_mtrr_aps_delayed_init();
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11
kernel/cpu.c
11
kernel/cpu.c
@ -386,6 +386,14 @@ out:
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#ifdef CONFIG_PM_SLEEP_SMP
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static cpumask_var_t frozen_cpus;
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void __weak arch_disable_nonboot_cpus_begin(void)
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{
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}
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void __weak arch_disable_nonboot_cpus_end(void)
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{
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}
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int disable_nonboot_cpus(void)
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{
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int cpu, first_cpu, error = 0;
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@ -397,6 +405,7 @@ int disable_nonboot_cpus(void)
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* with the userspace trying to use the CPU hotplug at the same time
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*/
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cpumask_clear(frozen_cpus);
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arch_disable_nonboot_cpus_begin();
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printk("Disabling non-boot CPUs ...\n");
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for_each_online_cpu(cpu) {
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@ -412,6 +421,8 @@ int disable_nonboot_cpus(void)
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}
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}
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arch_disable_nonboot_cpus_end();
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if (!error) {
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BUG_ON(num_online_cpus() > 1);
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/* Make sure the CPUs won't be enabled by someone else */
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