Re: Kswapd madness in 2.4 kernels

[Marcelo Tosatti]

On Wed, 6 Nov 2002, Andrea Arcangeli wrote:

> On Tue, Nov 05, 2002 at 02:13:00PM -0800, James Cleverdon wrote:
> > Status report:
> >
> > Due to dependencies, I didn't try the two recommended patches alone.  I ran
> > Andrea's 2.4.20-pre10aa1 kernel on the test load for one week.  Low memory
> > was conserved and kswapd never went out of control.  Presumably,
> > 05_vm_16_active_free_zone_bhs-1 did the job for buffers, and the inode patch
> > continued to work.
>
> yes, for stability the related-bh patch is known to be more than enough
> and this is a nice confirmation. I would also like to integrated some
> bit of andrew's nuke-buffer patch for performance reasons (to maximize
> the free memory utilization), not for stability. For stability teaching
> the VM about the problem is the right fix IMHO, good to have regardless
> in case for some reason the bh cannot be nucked if we can't take a lock
> or similar. But the bit that drops the bhs after reads may improve
> memory utilization when there is no memory pressure at all. The part I
> wouldn't merge in 2.4 from the Andrew's patch is the drop after writes,
> that has the potential of slowing down rewrite. I'm not saying it will
> slow down the rewrite performance, but there is definitely the
> potential. My fix instead has no way to affect read/writes w/o memory
> pressure compared to mainline (i.e. in a <1G machine).
>
> > Are there any plans on getting these into 2.4.21?

I will look closely at -aa during 2.4.21-pre stage, yes.

Andrea, please bug me on that.