[merged] zsmalloc-introduce-zs_can_compact-function.patch removed from -mm tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The patch titled
     Subject: zsmalloc: introduce zs_can_compact() function
has been removed from the -mm tree.  Its filename was
     zsmalloc-introduce-zs_can_compact-function.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Subject: zsmalloc: introduce zs_can_compact() function

This function checks if class compaction will free any pages.  Rephrasing
-- do we have enough unused objects to form at least one ZS_EMPTY page and
free it.  It aborts compaction if class compaction will not result in any
(further) savings.

EXAMPLE (this debug output is not part of this patch set):

-- class size
-- number of allocated objects
-- number of used objects
-- max objects per zspage
-- pages per zspage
-- estimated number of pages that will be freed

[..]
class-512 objs:544 inuse:540 maxobj-per-zspage:8  pages-per-zspage:1 zspages-to-free:0
 ... class-512 compaction is useless. break
class-496 objs:660 inuse:570 maxobj-per-zspage:33 pages-per-zspage:4 zspages-to-free:2
class-496 objs:627 inuse:570 maxobj-per-zspage:33 pages-per-zspage:4 zspages-to-free:1
class-496 objs:594 inuse:570 maxobj-per-zspage:33 pages-per-zspage:4 zspages-to-free:0
 ... class-496 compaction is useless. break
class-448 objs:657 inuse:617 maxobj-per-zspage:9  pages-per-zspage:1 zspages-to-free:4
class-448 objs:648 inuse:617 maxobj-per-zspage:9  pages-per-zspage:1 zspages-to-free:3
class-448 objs:639 inuse:617 maxobj-per-zspage:9  pages-per-zspage:1 zspages-to-free:2
class-448 objs:630 inuse:617 maxobj-per-zspage:9  pages-per-zspage:1 zspages-to-free:1
class-448 objs:621 inuse:617 maxobj-per-zspage:9  pages-per-zspage:1 zspages-to-free:0
 ... class-448 compaction is useless. break
class-432 objs:728 inuse:685 maxobj-per-zspage:28 pages-per-zspage:3 zspages-to-free:1
class-432 objs:700 inuse:685 maxobj-per-zspage:28 pages-per-zspage:3 zspages-to-free:0
 ... class-432 compaction is useless. break
class-416 objs:819 inuse:705 maxobj-per-zspage:39 pages-per-zspage:4 zspages-to-free:2
class-416 objs:780 inuse:705 maxobj-per-zspage:39 pages-per-zspage:4 zspages-to-free:1
class-416 objs:741 inuse:705 maxobj-per-zspage:39 pages-per-zspage:4 zspages-to-free:0
 ... class-416 compaction is useless. break
class-400 objs:690 inuse:674 maxobj-per-zspage:10 pages-per-zspage:1 zspages-to-free:1
class-400 objs:680 inuse:674 maxobj-per-zspage:10 pages-per-zspage:1 zspages-to-free:0
 ... class-400 compaction is useless. break
class-384 objs:736 inuse:709 maxobj-per-zspage:32 pages-per-zspage:3 zspages-to-free:0
 ... class-384 compaction is useless. break
[..]

Every "compaction is useless" indicates that we saved CPU cycles.

class-512 has
	544	object allocated
	540	objects used
	8	objects per-page

Even if we have a ALMOST_EMPTY zspage, we still don't have enough room to
migrate all of its objects and free this zspage; so compaction will not
make a lot of sense, it's better to just leave it as is.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/zsmalloc.c |   26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff -puN mm/zsmalloc.c~zsmalloc-introduce-zs_can_compact-function mm/zsmalloc.c
--- a/mm/zsmalloc.c~zsmalloc-introduce-zs_can_compact-function
+++ a/mm/zsmalloc.c
@@ -1676,6 +1676,29 @@ static struct page *isolate_source_page(
 	return page;
 }
 
+/*
+ *
+ * Based on the number of unused allocated objects calculate
+ * and return the number of pages that we can free.
+ *
+ * Should be called under class->lock.
+ */
+static unsigned long zs_can_compact(struct size_class *class)
+{
+	unsigned long obj_wasted;
+
+	if (!zs_stat_get(class, CLASS_ALMOST_EMPTY))
+		return 0;
+
+	obj_wasted = zs_stat_get(class, OBJ_ALLOCATED) -
+		zs_stat_get(class, OBJ_USED);
+
+	obj_wasted /= get_maxobj_per_zspage(class->size,
+			class->pages_per_zspage);
+
+	return obj_wasted * get_pages_per_zspage(class->size);
+}
+
 static unsigned long __zs_compact(struct zs_pool *pool,
 				struct size_class *class)
 {
@@ -1689,6 +1712,9 @@ static unsigned long __zs_compact(struct
 
 		BUG_ON(!is_first_page(src_page));
 
+		if (!zs_can_compact(class))
+			break;
+
 		cc.index = 0;
 		cc.s_page = src_page;
 
_

Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are


--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Kernel Newbies FAQ]     [Kernel Archive]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [Bugtraq]     [Photo]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]

  Powered by Linux