Re: [PATCH v3 8/8] mm/zsmalloc: add per-class compact trace event

[Minchan Kim]

Hello Ganesh,

On Wed, Jul 06, 2016 at 02:23:53PM +0800, Ganesh Mahendran wrote:
> add per-class compact trace event to get scanned objects and freed pages
> number.
> trace log is like below:
> ----
>          kswapd0-629   [001] ....   293.161053: zs_compact_start: pool zram0
>          kswapd0-629   [001] ....   293.161056: zs_compact: class 254: 0 objects scanned, 0 pages freed
>          kswapd0-629   [001] ....   293.161057: zs_compact: class 202: 0 objects scanned, 0 pages freed
>          kswapd0-629   [001] ....   293.161062: zs_compact: class 190: 1 objects scanned, 3 pages freed
>          kswapd0-629   [001] ....   293.161063: zs_compact: class 168: 0 objects scanned, 0 pages freed
>          kswapd0-629   [001] ....   293.161065: zs_compact: class 151: 0 objects scanned, 0 pages freed
>          kswapd0-629   [001] ....   293.161073: zs_compact: class 144: 4 objects scanned, 8 pages freed
>          kswapd0-629   [001] ....   293.161087: zs_compact: class 126: 20 objects scanned, 10 pages freed
>          kswapd0-629   [001] ....   293.161095: zs_compact: class 111: 6 objects scanned, 8 pages freed
>          kswapd0-629   [001] ....   293.161122: zs_compact: class 107: 27 objects scanned, 27 pages freed
>          kswapd0-629   [001] ....   293.161157: zs_compact: class 100: 36 objects scanned, 24 pages freed
>          kswapd0-629   [001] ....   293.161173: zs_compact: class  94: 10 objects scanned, 15 pages freed
>          kswapd0-629   [001] ....   293.161221: zs_compact: class  91: 30 objects scanned, 40 pages freed
>          kswapd0-629   [001] ....   293.161256: zs_compact: class  83: 120 objects scanned, 30 pages freed
>          kswapd0-629   [001] ....   293.161266: zs_compact: class  76: 8 objects scanned, 8 pages freed
>          kswapd0-629   [001] ....   293.161282: zs_compact: class  74: 20 objects scanned, 15 pages freed
>          kswapd0-629   [001] ....   293.161306: zs_compact: class  71: 40 objects scanned, 20 pages freed
>          kswapd0-629   [001] ....   293.161313: zs_compact: class  67: 8 objects scanned, 6 pages freed
> ...
>          kswapd0-629   [001] ....   293.161454: zs_compact: class   0: 0 objects scanned, 0 pages freed
>          kswapd0-629   [001] ....   293.161455: zs_compact_end: pool zram0: 301 pages compacted
> ----
> 
> Also this patch changes trace_zsmalloc_compact_start[end] to
> trace_zs_compact_start[end] to keep function naming consistent
> with others in zsmalloc.
> 
> Signed-off-by: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>
> ----
> v3:
>     add per-class compact trace event - Minchan
> 
>     I put this patch from 1/8 to 8/8, since this patch depends on below patch:
>        mm/zsmalloc: use obj_index to keep consistent with others
>        mm/zsmalloc: take obj index back from find_alloced_obj
> 

Thanks for looking into this, Ganesh!

Small change I want is to see the number of migrated object rather than
the number of scanning object.

If you don't mind, could you resend it with below?

Thanks.

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 3a1315e54057..166232a0aed6 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1774,7 +1774,7 @@ struct zs_compact_control {
 	 * in the subpage. */
 	int obj_idx;
 
-	unsigned long nr_scanned_obj;
+	unsigned long nr_migrated_obj;
 	unsigned long nr_freed_pages;
 };
 
@@ -1809,6 +1809,7 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
 		free_obj = obj_malloc(class, get_zspage(d_page), handle);
 		zs_object_copy(class, free_obj, used_obj);
 		obj_idx++;
+		cc->nr_migrated_obj++;
 		/*
 		 * record_obj updates handle's value to free_obj and it will
 		 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
@@ -1821,8 +1822,6 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
 		obj_free(class, used_obj);
 	}
 
-	cc->nr_scanned_obj += obj_idx - cc->obj_idx;
-
 	/* Remember last position in this iteration */
 	cc->s_page = s_page;
 	cc->obj_idx = obj_idx;
@@ -2270,7 +2269,7 @@ static unsigned long zs_can_compact(struct size_class *class)
 static void __zs_compact(struct zs_pool *pool, struct size_class *class)
 {
 	struct zs_compact_control cc = {
-		.nr_scanned_obj = 0,
+		.nr_migrated_obj = 0,
 		.nr_freed_pages = 0,
 	};
 	struct zspage *src_zspage;
@@ -2317,7 +2316,7 @@ static void __zs_compact(struct zs_pool *pool, struct size_class *class)
 	spin_unlock(&class->lock);
 
 	pool->stats.pages_compacted += cc.nr_freed_pages;
-	trace_zs_compact(class->index, cc.nr_scanned_obj, cc.nr_freed_pages);
+	trace_zs_compact(class->index, cc.nr_migrated_obj, cc.nr_freed_pages);
 }
 
 unsigned long zs_compact(struct zs_pool *pool)