From 621aa90178545c639c0d3cba71dd9c2435d3a822 Mon Sep 17 00:00:00 2001 From: Alexey Romanov Date: Thu, 27 Oct 2022 13:26:43 +0900 Subject: [PATCH] zram: add size class equals check into recompression 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@chromium.org Link: https://lkml.kernel.org/r/20221027042651.234524-2-senozhatsky@chromium.org Signed-off-by: Alexey Romanov Cc: Minchan Kim Cc: Nitin Gupta Signed-off-by: Andrew Morton --- drivers/block/zram/zram_drv.c | 5 +++++ include/linux/zsmalloc.h | 2 ++ mm/zsmalloc.c | 21 +++++++++++++++++++++ 3 files changed, 28 insertions(+) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 364323713393b6..fd31beb6491a36 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1632,6 +1632,8 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, 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 *zram, u32 index, struct page *page, 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 *zram, u32 index, struct page *page, */ 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); diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h index 2a430e713ce513..a48cd0ffe57dda 100644 --- a/include/linux/zsmalloc.h +++ b/include/linux/zsmalloc.h @@ -55,5 +55,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle); 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 diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index d03941cace2c49..065744b7e9d860 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1205,6 +1205,27 @@ static bool zspage_full(struct size_class *class, struct zspage *zspage) 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);