Re: [PATCH] mm, swap: Make VMA based swap readahead configurable

[Andrew Morton]

On Mon, 2 Oct 2017 08:45:40 -0700 Dave Hansen <dave.hansen@xxxxxxxxx> wrote:

> On 09/27/2017 06:02 PM, Huang, Ying wrote:
> > I still think there may be a performance regression for some users
> > because of the change of the algorithm and the knobs, and the
> > performance regression can be resolved via setting the new knob.  But I
> > don't think there will be a functionality regression.  Do you agree?
> 
> A performance regression is a regression.  I don't understand why we are
> splitting hairs as to what kind of regression it is.
> 

Yes.

Ying, please find us a way of avoiding any disruption to existing
system setups.  One which doesn't require that the operator perform a
configuration change to restore prior behaviour/performance.  And
please let's get this done well in advance of the 4.14 release.

Thanks.