Re: [PATCH 8/8] zramctl: allow use of --algorithm and --streams alone

Karel Zak
2014-08-06T08:20:29Z

On Tue, Aug 05, 2014 at 11:36:59PM +0100, Sami Kerola wrote:
> On 4 August 2014 12:55, Karel Zak <kzak@redhat.com> wrote:
> > On Mon, Aug 04, 2014 at 12:08:10AM +0100, Sami Kerola wrote:
> >> Earlier the --algorithm and --streams had to be combined with --size. To
> >> user requirement to combine with --size was indirectly told using
> >> following message.
> >
> > And is it really supported by kernel? I see in
> > Documentation/blockdev/zram.txt:
> >
> > In order to enable compression backend's multi stream support
> > max_comp_streams must be initially set to desired concurrency
> > level before ZRAM device initialisation.
> >
> > I guess that when you set disksize the zram device is "locked" for
> > setting changes. It means that modify already initialized (created)
> > zram devices is impossible. You have to reset the device to "unlock"
> > the device setting.
>
> After playing with zramctl I found out --algorithm must be set before
> --size. The --streams can be set after --size, but not if device is in use.
> When device is in use none of the settings are allowed.

I'd like to keep the command line semantic simple and stupid and
support --streams and --algorithm for device initialization (it means
with --size) only. We don't have to export to command line all the
crazy kernel implementation details.

Karel

--
Karel Zak <kzak@redhat.com>