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010b495e2f
Patch series "zsmalloc/zram: drop zram's max_zpage_size", v3. ZRAM's max_zpage_size is a bad thing. It forces zsmalloc to store normal objects as huge ones, which results in bigger zsmalloc memory usage. Drop it and use actual zsmalloc huge-class value when decide if the object is huge or not. This patch (of 2): Not every object can be share its zspage with other objects, e.g. when the object is as big as zspage or nearly as big a zspage. For such objects zsmalloc has a so called huge class - every object which belongs to huge class consumes the entire zspage (which consists of a physical page). On x86_64, PAGE_SHIFT 12 box, the first non-huge class size is 3264, so starting down from size 3264, objects can share page(-s) and thus minimize memory wastage. ZRAM, however, has its own statically defined watermark for huge objects, namely "3 * PAGE_SIZE / 4 = 3072", and forcibly stores every object larger than this watermark (3072) as a PAGE_SIZE object, in other words, to a huge class, while zsmalloc can keep some of those objects in non-huge classes. This results in increased memory consumption. zsmalloc knows better if the object is huge or not. Introduce zs_huge_class_size() function which tells if the given object can be stored in one of non-huge classes or not. This will let us to drop ZRAM's huge object watermark and fully rely on zsmalloc when we decide if the object is huge. [sergey.senozhatsky.work@gmail.com: add pool param to zs_huge_class_size()] Link: http://lkml.kernel.org/r/20180314081833.1096-2-sergey.senozhatsky@gmail.com Link: http://lkml.kernel.org/r/20180306070639.7389-2-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/*
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* zsmalloc memory allocator
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*
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* Copyright (C) 2011 Nitin Gupta
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* Copyright (C) 2012, 2013 Minchan Kim
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the license that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*/
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#ifndef _ZS_MALLOC_H_
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#define _ZS_MALLOC_H_
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#include <linux/types.h>
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/*
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* zsmalloc mapping modes
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*
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* NOTE: These only make a difference when a mapped object spans pages.
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* They also have no effect when PGTABLE_MAPPING is selected.
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*/
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enum zs_mapmode {
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ZS_MM_RW, /* normal read-write mapping */
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ZS_MM_RO, /* read-only (no copy-out at unmap time) */
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ZS_MM_WO /* write-only (no copy-in at map time) */
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/*
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* NOTE: ZS_MM_WO should only be used for initializing new
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* (uninitialized) allocations. Partial writes to already
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* initialized allocations should use ZS_MM_RW to preserve the
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* existing data.
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*/
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};
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struct zs_pool_stats {
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/* How many pages were migrated (freed) */
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unsigned long pages_compacted;
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};
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struct zs_pool;
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struct zs_pool *zs_create_pool(const char *name);
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void zs_destroy_pool(struct zs_pool *pool);
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unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t flags);
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void zs_free(struct zs_pool *pool, unsigned long obj);
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size_t zs_huge_class_size(struct zs_pool *pool);
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void *zs_map_object(struct zs_pool *pool, unsigned long handle,
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enum zs_mapmode mm);
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void zs_unmap_object(struct zs_pool *pool, unsigned long handle);
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unsigned long zs_get_total_pages(struct zs_pool *pool);
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unsigned long zs_compact(struct zs_pool *pool);
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void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats);
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#endif
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