linux/fs/squashfs/decompressor_multi_percpu.c
Xiaoming Ni 80f784098f squashfs: add the mount parameter theads=<single|multi|percpu>
Patch series 'squashfs: Add the mount parameter "threads="'.

Currently, Squashfs supports multiple decompressor parallel modes. 
However, this mode can be configured only during kernel building and does
not support flexible selection during runtime.

In the current patch set, the mount parameter "threads=" is added to allow
users to select the parallel decompressor mode and configure the number of
decompressors when mounting a file system.

"threads=<single|multi|percpu|1|2|3|...>"
The upper limit is num_online_cpus() * 2.


This patch (of 2):

Squashfs supports three decompression concurrency modes:
	Single-thread mode: concurrent reads are blocked and the memory
		overhead is small.
	Multi-thread mode/percpu mode: reduces concurrent read blocking but
		increases memory overhead.

The corresponding schema must be fixed at compile time. During mounting,
the concurrent decompression mode cannot be adjusted based on file read
blocking.

The mount parameter theads=<single|multi|percpu> is added to select
the concurrent decompression mode of a single SquashFS file system
image.

Link: https://lkml.kernel.org/r/20221019030930.130456-1-nixiaoming@huawei.com
Link: https://lkml.kernel.org/r/20221019030930.130456-2-nixiaoming@huawei.com
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Reviewed-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: Jianguo Chen <chenjianguo3@huawei.com>
Cc: Jubin Zhong <zhongjubin@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-18 13:55:08 -08:00

112 lines
2.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2013
* Phillip Lougher <phillip@squashfs.org.uk>
*/
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/percpu.h>
#include <linux/buffer_head.h>
#include <linux/local_lock.h>
#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;
local_lock_t lock;
};
static 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;
}
local_lock_init(&stream->lock);
}
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);
}
static 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);
}
}
static int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,
int offset, int length, struct squashfs_page_actor *output)
{
struct squashfs_stream *stream;
struct squashfs_stream __percpu *percpu =
(struct squashfs_stream __percpu *) msblk->stream;
int res;
local_lock(&percpu->lock);
stream = this_cpu_ptr(percpu);
res = msblk->decompressor->decompress(msblk, stream->stream, bio,
offset, length, output);
local_unlock(&percpu->lock);
if (res < 0)
ERROR("%s decompression failed, data probably corrupt\n",
msblk->decompressor->name);
return res;
}
static int squashfs_max_decompressors(void)
{
return num_possible_cpus();
}
const struct squashfs_decompressor_thread_ops squashfs_decompressor_percpu = {
.create = squashfs_decompressor_create,
.destroy = squashfs_decompressor_destroy,
.decompress = squashfs_decompress,
.max_decompressors = squashfs_max_decompressors,
};