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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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3bb5d2ee39
percpu areas are already allocated during boot for each possible cpu. percpu idle threads can be considered as an extension of the percpu areas, and allocate them for each possible cpu during boot. This will eliminate the need for workqueue based idle thread allocation. In future we can move the idle thread area into the percpu area too. [ tglx: Moved the loop into smpboot.c and added an error check when the init code failed to allocate an idle thread for a cpu which should be onlined ] Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: venki@google.com Link: http://lkml.kernel.org/r/1334966930.28674.245.camel@sbsiddha-desk.sc.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
63 lines
1.2 KiB
C
63 lines
1.2 KiB
C
/*
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* Common SMP CPU bringup/teardown functions
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*/
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#include <linux/err.h>
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#include <linux/smp.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/percpu.h>
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#include "smpboot.h"
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#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
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/*
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* For the hotplug case we keep the task structs around and reuse
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* them.
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*/
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static DEFINE_PER_CPU(struct task_struct *, idle_threads);
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struct task_struct * __cpuinit idle_thread_get(unsigned int cpu)
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{
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struct task_struct *tsk = per_cpu(idle_threads, cpu);
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if (!tsk)
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return ERR_PTR(-ENOMEM);
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init_idle(tsk, cpu);
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return tsk;
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}
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void __init idle_thread_set_boot_cpu(void)
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{
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per_cpu(idle_threads, smp_processor_id()) = current;
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}
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static inline void idle_init(unsigned int cpu)
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{
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struct task_struct *tsk = per_cpu(idle_threads, cpu);
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if (!tsk) {
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tsk = fork_idle(cpu);
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if (IS_ERR(tsk))
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pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
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else
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per_cpu(idle_threads, cpu) = tsk;
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}
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}
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/**
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* idle_thread_init - Initialize the idle thread for a cpu
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* @cpu: The cpu for which the idle thread should be initialized
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*
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* Creates the thread if it does not exist.
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*/
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void __init idle_threads_init(void)
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{
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unsigned int cpu;
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for_each_possible_cpu(cpu) {
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if (cpu != smp_processor_id())
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idle_init(cpu);
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}
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}
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#endif
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