Messages in this thread | | | Date | Tue, 1 Jul 2014 16:44:15 +0200 | From | David Sterba <> | Subject | Re: [PATCH] btrfs compression: merge inflate and deflate z_streams |
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On Tue, Jul 01, 2014 at 12:32:10AM +0900, Sergey Senozhatsky wrote: > `struct workspace' used for zlib compression contains two zlib > z_stream-s: `def_strm' used in zlib_compress_pages(), and `inf_strm' > used in zlib_decompress/zlib_decompress_biovec(). None of these > functions use `inf_strm' and `def_strm' simultaniously, meaning that > for every compress/decompress operation we need only one z_stream > (out of two available). > > `inf_strm' and `def_strm' are different in size of ->workspace. For > inflate stream we vmalloc() zlib_inflate_workspacesize() bytes, for > deflate stream - zlib_deflate_workspacesize() bytes. On my system zlib > returns the following workspace sizes, correspondingly: 42312 and 268104 > (+ guard pages). > > Keep only one `z_stream' in `struct workspace' and use it for both > compression and decompression. Hence, instead of vmalloc() of two > z_stream->worskpace-s, allocate only one of size: > max(zlib_deflate_workspacesize(), zlib_inflate_workspacesize()) > > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
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