Messages in this thread Patch in this message | | | From | Daniel Walker <> | Subject | [PATCH 1/2] fs/squashfs: Make SquashFS xz initialization mode configurable | Date | Fri, 8 Nov 2019 12:00:39 -0800 |
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From: "yusun2@cisco.com" <yusun2@cisco.com>
Make SquashFS xz initialization mode configurable to be either XZ_PREALLOC or XZ_DYNALLOC. The default mode is XZ_PREALLOC.
SquashFS multi-threaded per-CPU decompressor is proven to effectively resolve the I/O bottleneck and boost the outcome of other boot time optimization technologies on some I/O bound platforms. However it allocates extra memory on per-processor per-mounted-package basis. Making XZ_DYNALLOC mode an option for the xz decompressor initialization in SquashFS minimizes the memory impact.
Signed-off-by: Yu Sun <yusun2@cisco.com> Cc: xe-linux-external@cisco.com Signed-off-by: Daniel Walker <dwalker@fifo99.com> --- fs/squashfs/Kconfig | 32 ++++++++++++++++++++++++++++++++ fs/squashfs/xz_wrapper.c | 6 +++++- 2 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig index 916e78fabcaa..9cf2ebf89374 100644 --- a/fs/squashfs/Kconfig +++ b/fs/squashfs/Kconfig @@ -223,3 +223,35 @@ config SQUASHFS_FRAGMENT_CACHE_SIZE Note there must be at least one cached fragment. Anything much more than three will probably not make much difference. + +choice + prompt "XZ decompressor operation mode" + depends on SQUASHFS_XZ + default SQUASHFS_XZ_DICT_PREALLOC + help + Squashfs now utilizes the two different multi-call modes of xz + decompression. They each exhibits various trade-offs between + decompression performance and memory consumption. + + If in doubt, select "XZ preallocated multi-call mode" + +config SQUASHFS_XZ_DICT_PREALLOC + bool "XZ preallocated multi-call mode" + help + Traditionally Squashfs has used XZ_PREALLOC operation mode for + xz decompression, under which the xz dictionary buffer is allocated + at initialization. + +config SQUASHFS_XZ_DICT_DYNALLOC + bool "XZ dynamic-allocated multi-call mode" + help + By default Squashfs uses XZ_PREALLOC operation mode for xz decompressor. + This, however, potentially lead to significant increase of memory + consumption, especially when SquashFS per-cpu multi-threaded + decompressor is applied. + + If the system has memory constraints, setting this option will force + SquashFS to use XZ_DYNALLOC mode, and thus reduce memory footprint. + In this case, the LZMA2 dictionary is allocated upon needed with the + required size. +endchoice diff --git a/fs/squashfs/xz_wrapper.c b/fs/squashfs/xz_wrapper.c index 4b2f2051a6dc..6d6946bb5e4c 100644 --- a/fs/squashfs/xz_wrapper.c +++ b/fs/squashfs/xz_wrapper.c @@ -90,7 +90,11 @@ static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff) goto failed; } - stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size); + if (IS_ENABLED(CONFIG_SQUASHFS_XZ_DICT_DYNALLOC)) { + stream->state = xz_dec_init(XZ_DYNALLOC, comp_opts->dict_size); + } else { + stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size); + } if (stream->state == NULL) { kfree(stream); err = -ENOMEM; -- 2.17.1
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