Re: [patch][rfc][rft] vm throughput 2.4.2-ac4

[Marcelo Tosatti]

Duh, ignore that message. 

While looking into "postponed messages" folder I found this and
accidentally sent this.

Sorry.

On Wed, 16 Jan 2002, Marcelo Tosatti wrote:

> 
> 
> On Wed, 28 Feb 2001, Mike Galbraith wrote:
> 
> > On Wed, 28 Feb 2001, Marcelo Tosatti wrote:
> > 
> > > On Wed, 28 Feb 2001, Mike Galbraith wrote:
> > >
> > > > > > Have you tried to use SWAP_SHIFT as 4 instead of 5 on a stock 2.4.2-ac5 to
> > > > > > see if the system still swaps out too much?
> > > > >
> > > > > Not yet, but will do.
> > >
> > > But what about swapping behaviour?
> > >
> > > It still swaps too much?
> > 
> > Yes.
> > 
> > (returning to study mode)
> 
> Ok, I'm stupid. Changing SWAP_SHIFT will just balance the nr of tasks and
> the per-task nr of scanned pte's, but the not (roughly) the total nr of
> ptes scanned. I thought it would decrease the number of scanned ptes from
> 3% (which the current in -ac code does) to 0.3% (which Linus tree does) of
> the total ptes.
> 
> The problem seems to be multiple users calling swap_out() with 3% of ptes
> being scanned. This will unmap ptes way too heavily for common workloads.
> 
> Its magic number tuning.. but nothing better can be done for 2.4, I think.