linux-kernel - [PATCH] hugetlb: cond_resched for set_max_huge_pages and follow_hugetlb

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Date:	Thu, 23 Jul 2015 14:54:31 -0700
From:	Spencer Baugh <sbaugh@...ern.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	David Rientjes <rientjes@...gle.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Mike Kravetz <mike.kravetz@...cle.com>,
	Luiz Capitulino <lcapitulino@...hat.com>,
	linux-mm@...ck.org (open list:MEMORY MANAGEMENT),
	linux-kernel@...r.kernel.org (open list)
Cc:	Joern Engel <joern@...estorage.com>,
	Spencer Baugh <Spencer.baugh@...estorage.com>,
	Joern Engel <joern@...fs.org>,
	Spencer Baugh <sbaugh@...ern.com>
Subject: [PATCH] hugetlb: cond_resched for set_max_huge_pages and follow_hugetlb_page

From: Joern Engel <joern@...fs.org>

~150ms scheduler latency for both observed in the wild.

Signed-off-by: Joern Engel <joern@...fs.org>
Signed-off-by: Spencer Baugh <sbaugh@...ern.com>
---
 mm/hugetlb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a8c3087..2eb6919 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1836,6 +1836,7 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
 			ret = alloc_fresh_gigantic_page(h, nodes_allowed);
 		else
 			ret = alloc_fresh_huge_page(h, nodes_allowed);
+		cond_resched();
 		spin_lock(&hugetlb_lock);
 		if (!ret)
 			goto out;
@@ -3521,6 +3522,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 				spin_unlock(ptl);
 			ret = hugetlb_fault(mm, vma, vaddr,
 				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
+			cond_resched();
 			if (!(ret & VM_FAULT_ERROR))
 				continue;
 
-- 
2.5.0.rc3

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