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Patch series "zram: Support multiple compression streams", v5. This series adds support for multiple compression streams. The main idea is that different compression algorithms have different characteristics and zram may benefit when it uses a combination of algorithms: a default algorithm that is faster but have lower compression rate and a secondary algorithm that can use higher compression rate at a price of slower compression/decompression. There are several use-case for this functionality: - huge pages re-compression: zstd or deflate can successfully compress huge pages (~50% of huge pages on my synthetic ChromeOS tests), IOW pages that lzo was not able to compress. - idle pages re-compression: idle/cold pages sit in the memory and we may reduce zsmalloc memory usage if we recompress those idle pages. Userspace has a number of ways to control the behavior and impact of zram recompression: what type of pages should be recompressed, size watermarks, etc. Please refer to documentation patch. This patch (of 13): The patch turns compression streams and compressor algorithm name struct zram members into arrays, so that we can have multiple compression streams support (in the next patches). The patch uses a rather explicit API for compressor selection: - Get primary (default) compression stream zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]) - Get secondary compression stream zcomp_stream_get(zram->comps[ZRAM_SECONDARY_COMP]) We use similar API for compression streams put(). At this point we always have just one compression stream, since CONFIG_ZRAM_MULTI_COMP is not yet defined. Link: https://lkml.kernel.org/r/20221109115047.2921851-1-senozhatsky@chromium.org Link: https://lkml.kernel.org/r/20221109115047.2921851-2-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Alexey Romanov <avromanov@sberdevices.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
43 lines
1.2 KiB
C
43 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2014 Sergey Senozhatsky.
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*/
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#ifndef _ZCOMP_H_
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#define _ZCOMP_H_
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#include <linux/local_lock.h>
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struct zcomp_strm {
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/* The members ->buffer and ->tfm are protected by ->lock. */
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local_lock_t lock;
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/* compression/decompression buffer */
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void *buffer;
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struct crypto_comp *tfm;
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};
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/* dynamic per-device compression frontend */
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struct zcomp {
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struct zcomp_strm __percpu *stream;
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const char *name;
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struct hlist_node node;
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};
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int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node);
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int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
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ssize_t zcomp_available_show(const char *comp, char *buf);
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bool zcomp_available_algorithm(const char *comp);
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struct zcomp *zcomp_create(const char *alg);
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void zcomp_destroy(struct zcomp *comp);
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struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
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void zcomp_stream_put(struct zcomp *comp);
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int zcomp_compress(struct zcomp_strm *zstrm,
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const void *src, unsigned int *dst_len);
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int zcomp_decompress(struct zcomp_strm *zstrm,
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const void *src, unsigned int src_len, void *dst);
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bool zcomp_set_max_streams(struct zcomp *comp, int num_strm);
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#endif /* _ZCOMP_H_ */
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