On Wed, Oct 31, 2018 at 11:11:08AM -0700, Nick Terrell wrote:
> From: Jennifer Liu <jenniferliu...@fb.com>
> 
> Adds zstd compression level support to btrfs. Zstd requires
> different amounts of memory for each level, so the design had
> to be modified to allow set_level() to allocate memory. We
> preallocate one workspace of the maximum size to guarantee
> forward progress. This feature is expected to be useful for
> read-mostly filesystems, or when creating images.
> 
> Benchmarks run in qemu on Intel x86 with a single core.
> The benchmark measures the time to copy the Silesia corpus [0] to
> a btrfs filesystem 10 times, then read it back.
> 
> The two important things to note are:
> - The decompression speed and memory remains constant.
>   The memory required to decompress is the same as level 1.
> - The compression speed and ratio will vary based on the source.
> 
> Level Ratio   Compression     Decompression   Compression Memory
> 1     2.59    153 MB/s        112 MB/s        0.8 MB
> 2     2.67    136 MB/s        113 MB/s        1.0 MB
> 3     2.72    106 MB/s        115 MB/s        1.3 MB
> 4     2.78    86  MB/s        109 MB/s        0.9 MB
> 5     2.83    69  MB/s        109 MB/s        1.4 MB
> 6     2.89    53  MB/s        110 MB/s        1.5 MB
> 7     2.91    40  MB/s        112 MB/s        1.4 MB
> 8     2.92    34  MB/s        110 MB/s        1.8 MB
> 9     2.93    27  MB/s        109 MB/s        1.8 MB
> 10    2.94    22  MB/s        109 MB/s        1.8 MB
> 11    2.95    17  MB/s        114 MB/s        1.8 MB
> 12    2.95    13  MB/s        113 MB/s        1.8 MB
> 13    2.95    10  MB/s        111 MB/s        2.3 MB
> 14    2.99    7   MB/s        110 MB/s        2.6 MB
> 15    3.03    6   MB/s        110 MB/s        2.6 MB
> 
> [0] http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia
> 
> Signed-off-by: Jennifer Liu <jenniferliu...@fb.com>
> Signed-off-by: Nick Terrell <terre...@fb.com>
> Reviewed-by: Omar Sandoval <osan...@fb.com>

Please split the patch to a series where each patch does one logical
thing.

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