Commit edb91dc0 authored by Dimitri Sivanich's avatar Dimitri Sivanich Committed by Tony Luck
Browse files

[IA64] smp_flush_tlb_mm() should only send IPI's to cpus in cpu_vm_mask 



Having flush_tlb_mm->smp_flush_tlb_mm() send an IPI to every cpu
on the system is occasionally triggering spin_lock contention in
generic_smp_call_function_interrupt().

Follow x86 arch's lead and only sends IPIs to the cpus in mm->cpu_vm_mask.

Experiments with this change have shown significant improvement in this
contention issue.

Signed-off-by: default avatarDimitri Sivanich <sivanich@sgi.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent c4cb768f

arch/ia64/kernel/smp.c

+5 −8
Original line number Diff line number Diff line
@@ -301,15 +301,12 @@ smp_flush_tlb_mm (struct mm_struct *mm) 
		return;

	}



	smp_call_function_mask(mm->cpu_vm_mask,

		(void (*)(void *))local_finish_flush_tlb_mm, mm, 1);

	local_irq_disable();

	local_finish_flush_tlb_mm(mm);

	local_irq_enable();

	preempt_enable();

	/*

	 * We could optimize this further by using mm->cpu_vm_mask to track which CPUs

	 * have been running in the address space.  It's not clear that this is worth the

	 * trouble though: to avoid races, we have to raise the IPI on the target CPU

	 * anyhow, and once a CPU is interrupted, the cost of local_flush_tlb_all() is

	 * rather trivial.

	 */

	on_each_cpu((void (*)(void *))local_finish_flush_tlb_mm, mm, 1);

}



void arch_send_call_function_single_ipi(int cpu)