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![Minchan Kim](/assets/img/avatar_default.png)
This patch provides core functions for migration of zsmalloc. Migraion policy is simple as follows. for each size class { while { src_page = get zs_page from ZS_ALMOST_EMPTY if (!src_page) break; dst_page = get zs_page from ZS_ALMOST_FULL if (!dst_page) dst_page = get zs_page from ZS_ALMOST_EMPTY if (!dst_page) break; migrate(from src_page, to dst_page); } } For migration, we need to identify which objects in zspage are allocated to migrate them out. We could know it by iterating of freed objects in a zspage because first_page of zspage keeps free objects singly-linked list but it's not efficient. Instead, this patch adds a tag(ie, OBJ_ALLOCATED_TAG) in header of each object(ie, handle) so we could check whether the object is allocated easily. This patch adds another status bit in handle to synchronize between user access through zs_map_object and migration. During migration, we cannot move objects user are using due to data coherency between old object and new object. [akpm@linux-foundation.org: zsmalloc.c needs sched.h for cond_resched()] Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Juneho Choi <juno.choi@lge.com> Cc: Gunho Lee <gunho.lee@lge.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjennings@variantweb.net> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
52 lines
1.5 KiB
C
52 lines
1.5 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;
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struct zs_pool *zs_create_pool(char *name, gfp_t flags);
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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);
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void zs_free(struct zs_pool *pool, unsigned long obj);
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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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#endif
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