d208383d64
Add a multi-threaded decompression implementation which uses
percpu variables.
Using percpu variables has advantages and disadvantages over
implementations which do not use percpu variables.
Advantages:
* the nature of percpu variables ensures decompression is
load-balanced across the multiple cores.
* simplicity.
Disadvantages: it limits decompression to one thread per core.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
/*
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* Copyright (c) 2013
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/percpu.h>
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#include <linux/buffer_head.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "decompressor.h"
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#include "squashfs.h"
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/*
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* This file implements multi-threaded decompression using percpu
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* variables, one thread per cpu core.
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*/
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struct squashfs_stream {
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void *stream;
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};
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void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
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void *comp_opts)
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{
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struct squashfs_stream *stream;
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struct squashfs_stream __percpu *percpu;
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int err, cpu;
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percpu = alloc_percpu(struct squashfs_stream);
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if (percpu == NULL)
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return ERR_PTR(-ENOMEM);
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for_each_possible_cpu(cpu) {
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stream = per_cpu_ptr(percpu, cpu);
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stream->stream = msblk->decompressor->init(msblk, comp_opts);
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if (IS_ERR(stream->stream)) {
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err = PTR_ERR(stream->stream);
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goto out;
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}
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}
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kfree(comp_opts);
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return (__force void *) percpu;
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out:
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for_each_possible_cpu(cpu) {
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stream = per_cpu_ptr(percpu, cpu);
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if (!IS_ERR_OR_NULL(stream->stream))
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msblk->decompressor->free(stream->stream);
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}
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free_percpu(percpu);
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return ERR_PTR(err);
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}
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void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
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{
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struct squashfs_stream __percpu *percpu =
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(struct squashfs_stream __percpu *) msblk->stream;
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struct squashfs_stream *stream;
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int cpu;
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if (msblk->stream) {
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for_each_possible_cpu(cpu) {
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stream = per_cpu_ptr(percpu, cpu);
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msblk->decompressor->free(stream->stream);
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}
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free_percpu(percpu);
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}
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}
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int squashfs_decompress(struct squashfs_sb_info *msblk,
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void **buffer, struct buffer_head **bh, int b, int offset, int length,
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int srclength, int pages)
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{
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struct squashfs_stream __percpu *percpu =
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(struct squashfs_stream __percpu *) msblk->stream;
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struct squashfs_stream *stream = get_cpu_ptr(percpu);
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int res = msblk->decompressor->decompress(msblk, stream->stream, buffer,
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bh, b, offset, length, srclength, pages);
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put_cpu_ptr(stream);
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if (res < 0)
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ERROR("%s decompression failed, data probably corrupt\n",
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msblk->decompressor->name);
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return res;
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}
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int squashfs_max_decompressors(void)
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{
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return num_possible_cpus();
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}
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