The patch titled
Subject: zsmalloc: account the number of compacted pages
has been added to the -mm tree. Its filename is
zsmalloc-account-the-number-of-compacted-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zsmalloc-account-the-number-of-compacted-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zsmalloc-account-the-number-of-compacted-pages.patch
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------------------------------------------------------
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Subject: zsmalloc: account the number of compacted pages
Compaction returns back to zram the number of migrated objects, which is
quite uninformative -- we have objects of different sizes so user space
cannot obtain any valuable data from that number. Change compaction to
operate in terms of pages and return back to compaction issuer the number
of pages that were freed during compaction. So from now on we will export
more meaningful value in zram<id>/mm_stat -- the number of freed
(compacted) pages.
This requires:
(a) a rename of `num_migrated' to 'pages_compacted'
(b) a internal API change -- return first_page's fullness_group
from putback_zspage(), so we know when putback_zspage() did
free_zspage(). It helps us to account compaction stats correctly.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/blockdev/zram.txt | 3 ++-
drivers/block/zram/zram_drv.c | 2 +-
include/linux/zsmalloc.h | 4 ++--
mm/zsmalloc.c | 27 +++++++++++++++++----------
4 files changed, 22 insertions(+), 14 deletions(-)
diff -puN Documentation/blockdev/zram.txt~zsmalloc-account-the-number-of-compacted-pages Documentation/blockdev/zram.txt
--- a/Documentation/blockdev/zram.txt~zsmalloc-account-the-number-of-compacted-pages
+++ a/Documentation/blockdev/zram.txt
@@ -144,7 +144,8 @@ mem_used_max RW the maximum amou
store compressed data
mem_limit RW the maximum amount of memory ZRAM can use to store
the compressed data
-num_migrated RO the number of objects migrated migrated by compaction
+pages_compacted RO the number of pages freed during compaction
+ (available only via zram<id>/mm_stat node)
compact WO trigger memory compaction
WARNING
diff -puN drivers/block/zram/zram_drv.c~zsmalloc-account-the-number-of-compacted-pages drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zsmalloc-account-the-number-of-compacted-pages
+++ a/drivers/block/zram/zram_drv.c
@@ -450,7 +450,7 @@ static ssize_t mm_stat_show(struct devic
zram->limit_pages << PAGE_SHIFT,
max_used << PAGE_SHIFT,
(u64)atomic64_read(&zram->stats.zero_pages),
- pool_stats.num_migrated);
+ pool_stats.pages_compacted);
up_read(&zram->init_lock);
return ret;
diff -puN include/linux/zsmalloc.h~zsmalloc-account-the-number-of-compacted-pages include/linux/zsmalloc.h
--- a/include/linux/zsmalloc.h~zsmalloc-account-the-number-of-compacted-pages
+++ a/include/linux/zsmalloc.h
@@ -35,8 +35,8 @@ enum zs_mapmode {
};
struct zs_pool_stats {
- /* How many objects were migrated */
- unsigned long num_migrated;
+ /* How many pages were migrated (freed) */
+ unsigned long pages_compacted;
};
struct zs_pool;
diff -puN mm/zsmalloc.c~zsmalloc-account-the-number-of-compacted-pages mm/zsmalloc.c
--- a/mm/zsmalloc.c~zsmalloc-account-the-number-of-compacted-pages
+++ a/mm/zsmalloc.c
@@ -1579,8 +1579,6 @@ struct zs_compact_control {
/* Starting object index within @s_page which used for live object
* in the subpage. */
int index;
- /* How many of objects were migrated */
- int nr_migrated;
};
static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
@@ -1617,7 +1615,6 @@ static int migrate_zspage(struct zs_pool
record_obj(handle, free_obj);
unpin_tag(handle);
obj_free(pool, class, used_obj);
- cc->nr_migrated++;
}
/* Remember last position in this iteration */
@@ -1643,8 +1640,17 @@ static struct page *isolate_target_page(
return page;
}
-static void putback_zspage(struct zs_pool *pool, struct size_class *class,
- struct page *first_page)
+/*
+ * putback_zspage - add @first_page into right class's fullness list
+ * @pool: target pool
+ * @class: destination class
+ * @first_page: target page
+ *
+ * Return @fist_page's fullness_group
+ */
+static enum fullness_group putback_zspage(struct zs_pool *pool,
+ struct size_class *class,
+ struct page *first_page)
{
enum fullness_group fullness;
@@ -1662,6 +1668,8 @@ static void putback_zspage(struct zs_poo
free_zspage(first_page);
}
+
+ return fullness;
}
static struct page *isolate_source_page(struct size_class *class)
@@ -1704,7 +1712,6 @@ static void __zs_compact(struct zs_pool
struct page *src_page;
struct page *dst_page = NULL;
- cc.nr_migrated = 0;
spin_lock(&class->lock);
while ((src_page = isolate_source_page(class))) {
@@ -1733,7 +1740,9 @@ static void __zs_compact(struct zs_pool
break;
putback_zspage(pool, class, dst_page);
- putback_zspage(pool, class, src_page);
+ if (putback_zspage(pool, class, src_page) == ZS_EMPTY)
+ pool->stats.pages_compacted +=
+ get_pages_per_zspage(class->size);
spin_unlock(&class->lock);
cond_resched();
spin_lock(&class->lock);
@@ -1742,8 +1751,6 @@ static void __zs_compact(struct zs_pool
if (src_page)
putback_zspage(pool, class, src_page);
- pool->stats.num_migrated += cc.nr_migrated;
-
spin_unlock(&class->lock);
}
@@ -1761,7 +1768,7 @@ unsigned long zs_compact(struct zs_pool
__zs_compact(pool, class);
}
- return pool->stats.num_migrated;
+ return pool->stats.pages_compacted;
}
EXPORT_SYMBOL_GPL(zs_compact);
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
zsmalloc-drop-unused-variable-nr_to_migrate.patch
zsmalloc-always-keep-per-class-stats.patch
zsmalloc-introduce-zs_can_compact-function.patch
zsmalloc-cosmetic-compaction-code-adjustments.patch
zsmalloc-zram-introduce-zs_pool_stats-api.patch
zsmalloc-account-the-number-of-compacted-pages.patch
zsmalloc-use-shrinker-to-trigger-auto-compaction.patch
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