[PATCH] mm: don't zero ballooned pages

From	Wei Wang <wei.w.wang@intel.com>
Newsgroups	linux.kernel
Subject	[PATCH] mm: don't zero ballooned pages
Date	2017-07-31 06:30 +0200
Message-ID	<u9av8-1yG-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Ballooned pages will be marked as MADV_DONTNEED by the hypervisor and
shouldn't be given to the host ksmd to scan. Therefore, it is not
necessary to zero ballooned pages, which is very time consuming when
the page amount is large. The ongoing fast balloon tests show that the
time to balloon 7G pages is increased from ~491ms to 2.8 seconds with
__GFP_ZERO added. So, this patch removes the flag.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 mm/balloon_compaction.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 9075aa5..b06d9fe 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -24,7 +24,7 @@ struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info)
 {
 	unsigned long flags;
 	struct page *page = alloc_page(balloon_mapping_gfp_mask() |
-				__GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_ZERO);
+				       __GFP_NOMEMALLOC | __GFP_NORETRY);
 	if (!page)
 		return NULL;
 
-- 
2.7.4

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[PATCH] mm: don't zero ballooned pages Wei Wang <wei.w.wang@intel.com> - 2017-07-31 06:30 +0200
  Re: [PATCH] mm: don't zero ballooned pages Michal Hocko <mhocko@kernel.org> - 2017-07-31 09:00 +0200
    Re: [PATCH] mm: don't zero ballooned pages Wei Wang <wei.w.wang@intel.com> - 2017-07-31 09:40 +0200
      Re: [PATCH] mm: don't zero ballooned pages Michal Hocko <mhocko@kernel.org> - 2017-07-31 09:50 +0200
        Re: [PATCH] mm: don't zero ballooned pages Wei Wang <wei.w.wang@intel.com> - 2017-07-31 10:40 +0200
      Re: [PATCH] mm: don't zero ballooned pages Michal Hocko <mhocko@kernel.org> - 2017-07-31 10:00 +0200
        Re: [PATCH] mm: don't zero ballooned pages Michal Hocko <mhocko@kernel.org> - 2017-07-31 10:40 +0200
          Re: [PATCH] mm: don't zero ballooned pages "Michael S. Tsirkin" <mst@redhat.com> - 2017-08-01 17:40 +0200
    Re: [PATCH] mm: don't zero ballooned pages ZhenweiPi <zhenwei.pi@youruncloud.com> - 2017-07-31 09:40 +0200

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