Re: [PATCH] vmpressure: implement strict mode

From: Minchan Kim
Date: Wed Jun 26 2013 - 04:20:42 EST


Hello Michal,

On Wed, Jun 26, 2013 at 09:59:21AM +0200, Michal Hocko wrote:
> On Wed 26-06-13 16:50:51, Minchan Kim wrote:
> > On Tue, Jun 25, 2013 at 05:51:29PM -0400, Luiz Capitulino wrote:
> > > Currently, applications are notified for the level they registered for
> > > _plus_ higher levels.
> > >
> > > This is a problem if the application wants to implement different
> > > actions for different levels. For example, an application might want
> > > to release 10% of its cache on level low, 50% on medium and 100% on
> > > critical. To do this, the application has to register a different fd
> > > for each event. However, fd low is always going to be notified and
> > > and all fds are going to be notified on level critical.
> > >
> > > Strict mode solves this problem by strictly notifiying the event
> > > an fd has registered for. It's optional. By default we still notify
> > > on higher levels.
> > >
> > > Signed-off-by: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
> > Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
> >
> > Shouldn't we make this default?
>
> The interface is not there for long but still, changing it is always
> quite tricky. And the users who care can be modified really easily so I
> would stick with the original default.

Yeb, I am not strong against to stick old at a moment but at least,
this patch makes more sense to me so I'd like to know why we didn't do it
from the beginning. Surely, Anton has a answer.

>
> --
> Michal Hocko
> SUSE Labs
>
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--
Kind regards,
Minchan Kim
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