linux-kernel - [PATCH 3/3] x86: mm: Account for the of CPUs that must be flushed during a TLB range flush

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Date:	Thu, 12 Dec 2013 11:55:09 +0000
From:	Mel Gorman <mgorman@...e.de>
To:	Alex Shi <alex.shi@...aro.org>
Cc:	H Peter Anvin <hpa@...or.com>, Linux-X86 <x86@...nel.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 3/3] x86: mm: Account for the of CPUs that must be flushed during a TLB range flush

X86 TLB range flushing uses a balance point to decide if a single global TLB
flush or multiple single page flushes would perform best.  This patch takes into
account how many CPUs must be flushed.

Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 arch/x86/mm/tlb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 09b8cb8..0cababa 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -217,6 +217,9 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	act_entries = mm->total_vm > act_entries ? act_entries : mm->total_vm;
 	nr_base_pages = (end - start) >> PAGE_SHIFT;
 
+	/* Take the number of CPUs to range flush into account */
+	nr_base_pages *= cpumask_weight(mm_cpumask(mm));
+
 	/* tlb_flushall_shift is on balance point, details in commit log */
 	if (nr_base_pages > act_entries || has_large_page(mm, start, end)) {
 		count_vm_event(NR_TLB_LOCAL_FLUSH_ALL);
-- 
1.8.4

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