Re: [PATCH] zswap: Same-filled pages handling

[Dan Streetman]

On Mon, Nov 20, 2017 at 6:46 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, 18 Oct 2017 10:48:32 +0000 Srividya Desireddy <srividya.dr@xxxxxxxxxxx> wrote:
>
> > +/* Enable/disable handling same-value filled pages (enabled by default) */
> > +static bool zswap_same_filled_pages_enabled = true;
> > +module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
> > +                bool, 0644);
>
> Do we actually need this?  Being able to disable the new feature shows
> a certain lack of confidence ;) I guess we can remove it later as that
> confidence grows.

No, it's not absolutely needed to have the param to enable/disable the
feature, but my concern is around how many pages actually benefit from
this, since it adds some overhead to check every page - the usefulness
of the feature depends entirely on the system workload.  So having a
way to disable it is helpful, for use cases that know it won't benefit
them.

>
> Please send a patch to document this parameter in
> Documentation/vm/zswap.txt.  And if you have time, please check that
> the rest of that file is up-to-date?

Srividya, can you send a patch to doc this feature please.

I'll check the rest of the file is correct.

>
> Thanks.
>