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SubjectRe: [PATCH 3/5] zswap: runtime enable/disable
On Tue, Jun 02, 2015 at 11:11:55AM -0400, Dan Streetman wrote:
> Change the "enabled" parameter to be configurable at runtime. Remove
> the enabled check from init(), and move it to the frontswap store()
> function; when enabled, pages will be stored, and when disabled, pages
> won't be stored.

I like this one. So much so I wrote it about 2 years ago :)

http://lkml.iu.edu/hypermail/linux/kernel/1307.2/04289.html

It didn't go in though and I forgot about it.

We need to update the documentation too (see my patch).

Thanks,
Seth

>
> Signed-off-by: Dan Streetman <ddstreet@ieee.org>
> ---
> mm/zswap.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 4249e82..e070b10 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -75,9 +75,10 @@ static u64 zswap_duplicate_entry;
> /*********************************
> * tunables
> **********************************/
> -/* Enable/disable zswap (disabled by default, fixed at boot for now) */
> -static bool zswap_enabled __read_mostly;
> -module_param_named(enabled, zswap_enabled, bool, 0444);
> +
> +/* Enable/disable zswap (disabled by default) */
> +static bool zswap_enabled;
> +module_param_named(enabled, zswap_enabled, bool, 0644);
>
> /* Compressor to be used by zswap (fixed at boot for now) */
> #define ZSWAP_COMPRESSOR_DEFAULT "lzo"
> @@ -648,6 +649,9 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
> u8 *src, *dst;
> struct zswap_header *zhdr;
>
> + if (!zswap_enabled)
> + return -EPERM;
> +
> if (!tree) {
> ret = -ENODEV;
> goto reject;
> @@ -901,9 +905,6 @@ static int __init init_zswap(void)
> {
> gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
>
> - if (!zswap_enabled)
> - return 0;
> -
> pr_info("loading zswap\n");
>
> zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
> --
> 2.1.0
>


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