Re: throttling dirtiers

Andrew Morton
2002-07-31T21:32:37Z

Rik van Riel wrote:
>
> On Wed, 31 Jul 2002, Benjamin LaHaise wrote:
> > On Wed, Jul 31, 2002 at 02:02:03PM -0700, Andrew Morton wrote:
> > > But let's back off a bit. The problem is that a process
> > > doing a large write() can penalise innocent processes which
> > > want to allocate memory.
> > >
> > > How to fix that?
> >
> > First off, make it obvious where we block in the allocation path (pawning
> > off all memory reaping to kswapd et al is an easy first step here). Then
> > make allocators cycle through on a FIFO basis by using something like the
> > page reservation patch I came up with a while ago. That'll give us an
> > easy place to change scheduling behaviour.
>
> These ingredients are already in 2.4-rmap.

It doesn't seem to work. The -ac kernel has weird stalls on storms
of ext3 writeback. It's quite irritating, although probably not to
do with the VM.

The scheduler in the -ac kernel is also bad. Start a kernel build
and things like X apps and gdb become hugely slow. 2.5 is like that
too. I'll be going back to Marcelo.