The patch titled
Subject: zram: add size class equals check into recompression
has been added to the -mm mm-unstable branch. Its filename is
zram-add-size-class-equals-check-into-recompression.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-add-size-class-equals-check-into-recompression.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: Alexey Romanov <avromanov@xxxxxxxxxxxxxx>
Subject: zram: add size class equals check into recompression
Date: Thu, 27 Oct 2022 13:26:43 +0900
Patch series "zsmalloc/zram: configurable zspage size", v3.
It makes no sense for us to recompress the object if it will be in the
same size class. We anyway don't get any memory gain. But, at the same
time, we get a CPU time overhead when inserting this object into zspage
and decompressing it afterwards.
Link: https://lkml.kernel.org/r/20221027042651.234524-1-senozhatsky@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20221027042651.234524-2-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Alexey Romanov <avromanov@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/drivers/block/zram/zram_drv.c~zram-add-size-class-equals-check-into-recompression
+++ a/drivers/block/zram/zram_drv.c
@@ -1632,6 +1632,8 @@ static int zram_recompress(struct zram *
unsigned long handle_next;
unsigned int comp_len_next;
unsigned int comp_len_prev;
+ unsigned int class_index_prev;
+ unsigned int class_index_next;
struct zcomp_strm *zstrm;
void *src, *dst;
int ret;
@@ -1656,6 +1658,8 @@ static int zram_recompress(struct zram *
ret = zcomp_compress(zstrm, src, &comp_len_next);
kunmap_atomic(src);
+ class_index_prev = zs_lookup_class_index(zram->mem_pool, comp_len_prev);
+ class_index_next = zs_lookup_class_index(zram->mem_pool, comp_len_next);
/*
* Either a compression error or we failed to compressed the object
* in a way that will save us memory. Mark the object so that we
@@ -1663,6 +1667,7 @@ static int zram_recompress(struct zram *
*/
if (comp_len_next >= huge_class_size ||
comp_len_next >= comp_len_prev ||
+ class_index_next >= class_index_prev ||
ret) {
zram_set_flag(zram, index, ZRAM_RECOMP_SKIP);
zram_clear_flag(zram, index, ZRAM_IDLE);
--- a/include/linux/zsmalloc.h~zram-add-size-class-equals-check-into-recompression
+++ a/include/linux/zsmalloc.h
@@ -55,5 +55,7 @@ void zs_unmap_object(struct zs_pool *poo
unsigned long zs_get_total_pages(struct zs_pool *pool);
unsigned long zs_compact(struct zs_pool *pool);
+unsigned int zs_lookup_class_index(struct zs_pool *pool, unsigned int size);
+
void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats);
#endif
--- a/mm/zsmalloc.c~zram-add-size-class-equals-check-into-recompression
+++ a/mm/zsmalloc.c
@@ -1205,6 +1205,27 @@ static bool zspage_full(struct size_clas
return get_zspage_inuse(zspage) == class->objs_per_zspage;
}
+/**
+ * zs_lookup_class_index() - Returns index of the zsmalloc &size_class
+ * that hold objects of the provided size.
+ * @pool: zsmalloc pool to use
+ * @size: object size
+ *
+ * Context: Any context.
+ *
+ * Return: the index of the zsmalloc &size_class that hold objects of the
+ * provided size.
+ */
+unsigned int zs_lookup_class_index(struct zs_pool *pool, unsigned int size)
+{
+ struct size_class *class;
+
+ class = pool->size_class[get_size_class_index(size)];
+
+ return class->index;
+}
+EXPORT_SYMBOL_GPL(zs_lookup_class_index);
+
unsigned long zs_get_total_pages(struct zs_pool *pool)
{
return atomic_long_read(&pool->pages_allocated);
_
Patches currently in -mm which might be from avromanov@xxxxxxxxxxxxxx are
zram-add-size-class-equals-check-into-recompression.patch
