Messages in this thread | | | Date | Wed, 30 May 2001 16:00:08 +0200 | From | Andrea Arcangeli <> | Subject | Re: [patch] 4GB I/O, cut three |
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[ my usual email is offline at the moment, please CC to andrea@e-mind.com for anything urgent until the problem is fixed ]
On Wed, May 30, 2001 at 11:55:38AM +0200, Jens Axboe wrote: > On Wed, May 30 2001, Mark Hemment wrote: > > Hi Jens, > > > > I ran this (well, cut-two) on a 4-way box with 4GB of memory and a > > modified qlogic fibre channel driver with 32disks hanging off it, without > > any problems. The test used was SpecFS 2.0 > > Cool, could you send me the qlogic diff? It's the one-liner can_dma32 > chance I'm interested in, I'm just not sure what driver you used :-) > I'll add that to the patch then. Basically all the PCI cards should > work, I'm just being cautious and only enabling highmem I/O to the ones > that have been tested. > > > Peformance is definitely up - but I can't give an exact number, as the > > run with this patch was compiled with no-omit-frame-pointer for debugging > > any probs. > > Good > > > I did change the patch so that bounce-pages always come from the NORMAL > > zone, hence the ZONE_DMA32 zone isn't needed. I avoided the new zone, as > > I'm not 100% sure the VM is capable of keeping the zones it already has > > balanced - and adding another one might break the camels back. But as the > > test box has 4GB, it wasn't bouncing anyway. > > You are right, this is definitely something that needs checking. I > really want this to work though. Rik, Andrea? Will the balancing handle > the extra zone?
The bounces can came from the ZONE_NORMAL without problems, however the ZONE_DMA32 way is fine too, but yes probably it isn't needed in real life unless you do an huge amount of I/O at the same time. If you want to reduce the amount of changes you can defer the zone_dma32 patch and possibly plug it in later.
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