The patch titled
Subject: mm, kmemleak: little optimization while scanning
has been added to the -mm tree. Its filename is
mm-kmemleak-little-optimization-while-scanning.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kmemleak-little-optimization-while-scanning.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kmemleak-little-optimization-while-scanning.patch
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------------------------------------------------------
From: Oscar Salvador <osalvador@xxxxxxx>
Subject: mm, kmemleak: little optimization while scanning
kmemleak_scan() goes through all online nodes and tries to scan all used
pages.
We can do better and use pfn_to_online_page(), so in case we have
CONFIG_MEMORY_HOTPLUG, offlined pages will be skiped automatically. For
boxes where CONFIG_MEMORY_HOTPLUG is not present, pfn_to_online_page()
will fallback to pfn_valid().
Another little optimization is to check if the page belongs to the node we
are currently checking, so in case we have nodes interleaved we will not
check the same pfn multiple times.
I ran some tests:
Add some memory to node1 and node2 making it interleaved:
(qemu) object_add memory-backend-ram,id=ram0,size=1G
(qemu) device_add pc-dimm,id=dimm0,memdev=ram0,node=1
(qemu) object_add memory-backend-ram,id=ram1,size=1G
(qemu) device_add pc-dimm,id=dimm1,memdev=ram1,node=2
(qemu) object_add memory-backend-ram,id=ram2,size=1G
(qemu) device_add pc-dimm,id=dimm2,memdev=ram2,node=1
Then, we offline that memory:
# for i in {32..39} ; do echo "offline" > /sys/devices/system/node/node1/memory$i/state;done
# for i in {48..55} ; do echo "offline" > /sys/devices/system/node/node1/memory$i/state;don
# for i in {40..47} ; do echo "offline" > /sys/devices/system/node/node2/memory$i/state;done
And we run kmemleak_scan:
# echo "scan" > /sys/kernel/debug/kmemleak
before the patch:
kmemleak: time spend: 41596 us
after the patch:
kmemleak: time spend: 34899 us
Link: http://lkml.kernel.org/r/20181206131918.25099-1-osalvador@xxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmemleak.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/mm/kmemleak.c~mm-kmemleak-little-optimization-while-scanning
+++ a/mm/kmemleak.c
@@ -113,6 +113,7 @@
#include <linux/kmemleak.h>
#include <linux/memory_hotplug.h>
+
/*
* Kmemleak configuration and common defines.
*/
@@ -1547,11 +1548,14 @@ static void kmemleak_scan(void)
unsigned long pfn;
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
- struct page *page;
+ struct page *page = pfn_to_online_page(pfn);
+
+ if (!page)
+ continue;
- if (!pfn_valid(pfn))
+ /* only scan pages belonging to this node */
+ if (page_to_nid(page) != i)
continue;
- page = pfn_to_page(pfn);
/* only scan if page is in use */
if (page_count(page) == 0)
continue;
_
Patches currently in -mm which might be from osalvador@xxxxxxx are
kernel-resource-check-for-ioresource_sysram-in-release_mem_region_adjustable.patch
mm-page_alloc-drop-uneeded-__meminit-and-__meminitdata.patch
mm-kmemleak-little-optimization-while-scanning.patch
