The patch titled
Subject: zsmalloc: do not scan for allocated objects in empty zspage
has been added to the -mm mm-unstable branch. Its filename is
zsmalloc-do-not-scan-for-allocated-objects-in-empty-zspage.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zsmalloc-do-not-scan-for-allocated-objects-in-empty-zspage.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zsmalloc: do not scan for allocated objects in empty zspage
Date: Sat, 24 Jun 2023 14:12:14 +0900
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@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Suggested-by: Alexey Romanov <AVRomanov@xxxxxxxxxxxxxx>
Reviewed-by: Alexey Romanov <avromanov@xxxxxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/mm/zsmalloc.c~zsmalloc-do-not-scan-for-allocated-objects-in-empty-zspage
+++ a/mm/zsmalloc.c
@@ -1147,6 +1147,11 @@ static bool zspage_full(struct size_clas
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_poo
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 */
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zsmalloc-do-not-scan-for-allocated-objects-in-empty-zspage.patch
zsmalloc-move-migration-destination-zspage-inuse-check.patch
