From d208383d640727b70cd6689bc17e67e9b5ebf4ff Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Mon, 18 Nov 2013 02:31:36 +0000 Subject: Squashfs: add multi-threaded decompression using percpu variable 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 --- fs/squashfs/decompressor_multi_percpu.c | 98 +++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 fs/squashfs/decompressor_multi_percpu.c (limited to 'fs/squashfs/decompressor_multi_percpu.c') diff --git a/fs/squashfs/decompressor_multi_percpu.c b/fs/squashfs/decompressor_multi_percpu.c new file mode 100644 index 000000000000..0e7b679bc4ad --- /dev/null +++ b/fs/squashfs/decompressor_multi_percpu.c @@ -0,0 +1,98 @@ +/* + * Copyright (c) 2013 + * Phillip Lougher + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + */ + +#include +#include +#include +#include + +#include "squashfs_fs.h" +#include "squashfs_fs_sb.h" +#include "decompressor.h" +#include "squashfs.h" + +/* + * This file implements multi-threaded decompression using percpu + * variables, one thread per cpu core. + */ + +struct squashfs_stream { + void *stream; +}; + +void *squashfs_decompressor_create(struct squashfs_sb_info *msblk, + void *comp_opts) +{ + struct squashfs_stream *stream; + struct squashfs_stream __percpu *percpu; + int err, cpu; + + percpu = alloc_percpu(struct squashfs_stream); + if (percpu == NULL) + return ERR_PTR(-ENOMEM); + + for_each_possible_cpu(cpu) { + stream = per_cpu_ptr(percpu, cpu); + stream->stream = msblk->decompressor->init(msblk, comp_opts); + if (IS_ERR(stream->stream)) { + err = PTR_ERR(stream->stream); + goto out; + } + } + + kfree(comp_opts); + return (__force void *) percpu; + +out: + for_each_possible_cpu(cpu) { + stream = per_cpu_ptr(percpu, cpu); + if (!IS_ERR_OR_NULL(stream->stream)) + msblk->decompressor->free(stream->stream); + } + free_percpu(percpu); + return ERR_PTR(err); +} + +void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk) +{ + struct squashfs_stream __percpu *percpu = + (struct squashfs_stream __percpu *) msblk->stream; + struct squashfs_stream *stream; + int cpu; + + if (msblk->stream) { + for_each_possible_cpu(cpu) { + stream = per_cpu_ptr(percpu, cpu); + msblk->decompressor->free(stream->stream); + } + free_percpu(percpu); + } +} + +int squashfs_decompress(struct squashfs_sb_info *msblk, + void **buffer, struct buffer_head **bh, int b, int offset, int length, + int srclength, int pages) +{ + struct squashfs_stream __percpu *percpu = + (struct squashfs_stream __percpu *) msblk->stream; + struct squashfs_stream *stream = get_cpu_ptr(percpu); + int res = msblk->decompressor->decompress(msblk, stream->stream, buffer, + bh, b, offset, length, srclength, pages); + put_cpu_ptr(stream); + + if (res < 0) + ERROR("%s decompression failed, data probably corrupt\n", + msblk->decompressor->name); + + return res; +} + +int squashfs_max_decompressors(void) +{ + return num_possible_cpus(); +} -- cgit v1.2.1