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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: Sergey Senozhatsky <senozhatsky@chromium.org>
Suggested-by: Alexey Romanov <AVRomanov@sberdevices.ru>
Reviewed-by: Alexey Romanov <avromanov@sberdevices.ru>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sergey Senozhatsky 2023-06-24 14:12:14 +09:00 committed by Andrew Morton
parent 3fade62b62
commit df9cd3cbf2
1 changed files with 9 additions and 0 deletions
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9
mm/zsmalloc.c
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@ -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 */