Re: [PATCH] Add option to configure default zswap compressor algorithm.

[Will Dignazio <wdignazio@gmail.com>]

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Apologies for bumping. I also should give a better description:

This patch introduces a configuration option for the default cryptographic
compression algorithm used by zswap. Previous to this patch, one would use
the default compression algorithm until changed from userspace. This patch
allows a compilation time change, which will remain the default from boot
until changed.

On Sat, Jun 30, 2018 at 11:56 PM Will Ziener-Dignazio <wdignazio@gmail.com>
wrote:

>     - Add Kconfig option for default compressor algorithm
>     - Add the deflate and LZ4 algorithms as default options
>
> Signed-off-by: Will Ziener-Dignazio <wdignazio@gmail.com>
> ---
>  mm/Kconfig | 35 ++++++++++++++++++++++++++++++++++-
>  mm/zswap.c | 11 ++++++++++-
>  2 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index ce95491abd6a..09df6650e96a 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -535,7 +535,6 @@ config MEM_SOFT_DIRTY
>  config ZSWAP
>         bool "Compressed cache for swap pages (EXPERIMENTAL)"
>         depends on FRONTSWAP && CRYPTO=y
> -       select CRYPTO_LZO
>         select ZPOOL
>         default n
>         help
> @@ -552,6 +551,40 @@ config ZSWAP
>           they have not be fully explored on the large set of potential
>           configurations and workloads that exist.
>
> +choice
> +       prompt "Compressed cache cryptographic compression algorithm"
> +       default ZSWAP_COMPRESSOR_DEFAULT_LZO
> +       depends on ZSWAP
> +       help
> +         The default cyptrographic compression algorithm to use for
> +         compressed swap pages.
> +
> +config ZSWAP_COMPRESSOR_DEFAULT_LZO
> +       bool "lzo"
> +       select CRYPTO_LZO
> +       help
> +         This option sets the default zswap compression algorithm to LZO,
> +         the Lempel-Ziv-Oberhumer algorithm. This algorthm focuses on
> +         decompression speed, but has a lower compression ratio.
> +
> +config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
> +       bool "deflate"
> +       select CRYPTO_DEFLATE
> +       help
> +         This option sets the default zswap compression algorithm to
> DEFLATE.
> +         This algorithm balances compression and decompression speed to
> +         compresstion ratio.
> +
> +config ZSWAP_COMPRESSOR_DEFAULT_LZ4
> +       bool "lz4"
> +       select CRYPTO_LZ4
> +       help
> +         This option sets the default zswap compression algorithm to LZ4.
> +         This algorithm focuses on high compression speed, but has a lower
> +         compression ratio and decompression speed.
> +
> +endchoice
> +
>  config ZPOOL
>         tristate "Common API for compressed memory storage"
>         default n
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 7d34e69507e3..30f9f25da4d0 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -91,7 +91,16 @@ static struct kernel_param_ops zswap_enabled_param_ops
> = {
>  module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
>
>  /* Crypto compressor to use */
> -#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
> +#if defined(CONFIG_ZSWAP_COMPRESSOR_DEFAULT_LZO)
> +  #define ZSWAP_COMPRESSOR_DEFAULT "lzo"
> +#elif defined(CONFIG_ZSWAP_COMPRESSOR_DEFAULT_DEFLATE)
> +  #define ZSWAP_COMPRESSOR_DEFAULT "deflate"
> +#elif defined(CONFIG_ZSWAP_COMPRESSOR_DEFAULT_LZ4)
> +  #define ZSWAP_COMPRESSOR_DEFAULT "lz4"
> +#else
> +  #error "Default zswap compression algorithm not defined."
> +#endif
> +
>  static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
>  static int zswap_compressor_param_set(const char *,
>                                       const struct kernel_param *);
> --
> 2.18.0
>
> --
Bytes Go In, Words Go Out

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