[IA64] smp_flush_tlb_mm() should only send IPI's to cpus in cpu_vm_mask (edb91dc0) · Commits · 戴 / test

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:

Dimitri Sivanich <sivanich@sgi.com> Signed-off-by:

Tony Luck <tony.luck@intel.com>

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)

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