Re: [PATCH] ksm: add vm_stat and meminfo entry to reflect pte mapping to ksm pages
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2011-03-01 23:41:23
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On Sat, 26 Feb 2011 22:56:31 +0800 Nai Xia [off-list ref] wrote:
ksm_pages_sharing is updated by ksmd periodically. In some cases, it cannot reflect the actual savings and makes the benchmarks on volatile VMAs very inaccurate. This patch add a vm_stat entry and let the /proc/meminfo show information about how much virutal address pte is being mapped to ksm pages. With default ksm paramters (pages_to_scan==100 && sleep_millisecs==20), this can result in 50% more accurate averaged savings result for the following test program. Bigger sleep_millisecs values will increase this deviation.
So I think you're saying that the existing ksm_pages_sharing sysfs file is no good. You added a new entry to /proc/meminfo and left ksm_pages_sharing as-is. Why not leave /proc/meminfo alone, and fix up the existing ksm_pages_sharing? Also, the patch accumulates the NR_KSM_PAGES_SHARING counts on a per-zone basis as well as on a global basis, but only provides the global count to userspace. The per-zone counts are potentially interesting? If not, maintaining the per-zone counters is wasted overhead.
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--- test.c-----
The "^---" token conventionally means "end of changelog". Please avoid inserting it into the middle of the changelog.
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+++ b/mm/ksm.c@@ -897,6 +897,7 @@ static int try_to_merge_one_page(struct vm_area_struct*vma,
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