Re: [PATCH] mm/zswap: change params from hidden to ro

From: Weijie Yang
Date: Wed Nov 20 2013 - 22:13:11 EST


On Thu, Nov 21, 2013 at 1:52 AM, Dan Streetman <ddstreet@xxxxxxxx> wrote:
> On Wed, Nov 20, 2013 at 12:33 PM, Vladimir Murzin <murzin.v@xxxxxxxxx> wrote:
>> Hi Dan!
>>
>> On Wed, Nov 20, 2013 at 11:38:42AM -0500, Dan Streetman wrote:
>>> The "compressor" and "enabled" params are currently hidden,
>>> this changes them to read-only, so userspace can tell if
>>> zswap is enabled or not and see what compressor is in use.
>>
>> Could you elaborate more why this pice of information is necessary for
>> userspace?
>
> For anyone interested in zswap, it's handy to be able to tell if it's
> enabled or not ;-) Technically people can check to see if the zswap
> debug files are in /sys/kernel/debug/zswap, but I think the actual
> "enabled" param is more obvious. And the compressor param is really
> the only way anyone from userspace can see what compressor's being
> used; that's helpful to know for anyone that might want to be using a
> non-default compressor.
>
> And of course, eventually we'll want to make the params writable, so
> the compressor can be changed dynamically, and zswap can be enabled or
> disabled dynamically (or at least enabled after boot).

Please do not make them writable.
There is no requirement to do that, and it will make zswap more complex.

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