Re: Terrible VM in 2.4.11+?

[Jens Axboe <axboe@suse.de>]

On Wed, Jul 10 2002, Thomas Tonino wrote:
> J.A. Magallon wrote:
> 
> >Seriously, if you have that kind of problems, take the -aa kernel and use 
> >it.
> >I use it regularly and it behaves as one would expect, and fast.
> >And please, report your results...
> 
> I run a 2 cpu server with 16 disks and around 5 megabytes of writes a 
> second. With plain 2.4.18 (using the feral.com qlogic driver) and 2GB 
> ram, this seemed okay. Upgrading to 4GB ram slowed the system down, and 
> normal shell commands became quite unresponsive with 4GB.
> 
> So we built a second server, with 2.4.19-pre9-aa2 using the qlogic 
> driver in the kernel. That driver needs patching, as it will otherwise 
> get stuck in a 'no handle slots' condition. Used a patch that I posted 
> to linux-scsi a while ago.

That's probably not just a mm issue, if you use stock 2.4.18 with 4GB
ram you will spend oodles of time bounce buffering i/o. 2.4.19-pre9-aa2
includes the block-highmem stuff, which enables direct-to-highmem i/o,
if you enabled the CONFIG_HIGHIO option.

In short, not an apples-to-apples comparison :-)

-- 
Jens Axboe