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authorMinchan Kim <minchan@kernel.org>2015-09-09 01:00:24 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-09 01:35:28 +0300
commit8334b96221ff0dcbde4873d31eb4d84774ed8ed4 (patch)
tree35c6f7a7ab427834a10c3e74ccedcac9911e588a /mm
parent3115aec4513e5bcb399235cac98a5637fe641c13 (diff)
downloadlinux-8334b96221ff0dcbde4873d31eb4d84774ed8ed4.tar.xz
mm: /proc/pid/smaps:: show proportional swap share of the mapping
We want to know per-process workingset size for smart memory management on userland and we use swap(ex, zram) heavily to maximize memory efficiency so workingset includes swap as well as RSS. On such system, if there are lots of shared anonymous pages, it's really hard to figure out exactly how many each process consumes memory(ie, rss + wap) if the system has lots of shared anonymous memory(e.g, android). This patch introduces SwapPss field on /proc/<pid>/smaps so we can get more exact workingset size per process. Bongkyu tested it. Result is below. 1. 50M used swap SwapTotal: 461976 kB SwapFree: 411192 kB $ adb shell cat /proc/*/smaps | grep "SwapPss:" | awk '{sum += $2} END {print sum}'; 48236 $ adb shell cat /proc/*/smaps | grep "Swap:" | awk '{sum += $2} END {print sum}'; 141184 2. 240M used swap SwapTotal: 461976 kB SwapFree: 216808 kB $ adb shell cat /proc/*/smaps | grep "SwapPss:" | awk '{sum += $2} END {print sum}'; 230315 $ adb shell cat /proc/*/smaps | grep "Swap:" | awk '{sum += $2} END {print sum}'; 1387744 [akpm@linux-foundation.org: simplify kunmap_atomic() call] Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Bongkyu Kim <bongkyu.kim@lge.com> Tested-by: Bongkyu Kim <bongkyu.kim@lge.com> Cc: Hugh Dickins <hughd@google.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/swapfile.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index aebc2dd6e649..58877312cf6b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -875,6 +875,48 @@ int page_swapcount(struct page *page)
}
/*
+ * How many references to @entry are currently swapped out?
+ * This considers COUNT_CONTINUED so it returns exact answer.
+ */
+int swp_swapcount(swp_entry_t entry)
+{
+ int count, tmp_count, n;
+ struct swap_info_struct *p;
+ struct page *page;
+ pgoff_t offset;
+ unsigned char *map;
+
+ p = swap_info_get(entry);
+ if (!p)
+ return 0;
+
+ count = swap_count(p->swap_map[swp_offset(entry)]);
+ if (!(count & COUNT_CONTINUED))
+ goto out;
+
+ count &= ~COUNT_CONTINUED;
+ n = SWAP_MAP_MAX + 1;
+
+ offset = swp_offset(entry);
+ page = vmalloc_to_page(p->swap_map + offset);
+ offset &= ~PAGE_MASK;
+ VM_BUG_ON(page_private(page) != SWP_CONTINUED);
+
+ do {
+ page = list_entry(page->lru.next, struct page, lru);
+ map = kmap_atomic(page);
+ tmp_count = map[offset];
+ kunmap_atomic(map);
+
+ count += (tmp_count & ~COUNT_CONTINUED) * n;
+ n *= (SWAP_CONT_MAX + 1);
+ } while (tmp_count & COUNT_CONTINUED);
+out:
+ spin_unlock(&p->lock);
+ return count;
+}
+
+/*
* We can write to an anon page without COW if there are no other references
* to it. And as a side-effect, free up its swap: because the old content
* on disk will never be read, and seeking back there to write new content