Commit df9cd3cb authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Andrew Morton
Browse files

zsmalloc: do not scan for allocated objects in empty zspage 

Patch series "zsmalloc: small compaction improvements", v2.

A tiny series that can reduce the number of find_alloced_obj() invocations
(which perform a linear scan of sub-page) during compaction.  Inspired by
Alexey Romanov's findings.


This patch (of 3):

zspage migration can terminate as soon as it moves the last allocated
object from the source zspage.  Add a simple helper zspage_empty() that
tests zspage ->inuse on each migration iteration.

Link: https://lkml.kernel.org/r/20230624053120.643409-2-senozhatsky@chromium.org


Signed-off-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Suggested-by: default avatarAlexey Romanov <AVRomanov@sberdevices.ru>
Reviewed-by: default avatarAlexey Romanov <avromanov@sberdevices.ru>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3fade62b

mm/zsmalloc.c

+9 −0
Original line number Diff line number Diff line
@@ -1147,6 +1147,11 @@ static bool zspage_full(struct size_class *class, struct zspage *zspage) 
	return get_zspage_inuse(zspage) == class->objs_per_zspage;

}



static bool zspage_empty(struct zspage *zspage)

{

	return get_zspage_inuse(zspage) == 0;

}



/**

 * zs_lookup_class_index() - Returns index of the zsmalloc &size_class

 * that hold objects of the provided size.
@@ -1625,6 +1630,10 @@ static void migrate_zspage(struct zs_pool *pool, struct size_class *class, 
		obj_idx++;

		record_obj(handle, free_obj);

		obj_free(class->size, used_obj);



		/* Stop if there are no more objects to migrate */

		if (zspage_empty(get_zspage(s_page)))

			break;

	}



	/* Remember last position in this iteration */