Messages in this thread | | | From | Andi Kleen <> | Subject | Re: adding swap workarounds oom - was: Re: Out of Memory: Killed process 16498 (java). | Date | Wed, 1 Mar 2006 15:26:38 +0100 |
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On Wednesday 01 March 2006 15:18, Jens Axboe wrote: > On Wed, Mar 01 2006, Andi Kleen wrote: > > On Wednesday 01 March 2006 14:41, Jens Axboe wrote: > > > On Wed, Mar 01 2006, Andy Chittenden wrote: > > > > with revised patch that does: > > > > > > > > printk("sg%d: dma=%llx, dma_len=%u/%u, pfn=%lu\n", i, > > > > (unsigned long long) sg->dma_address, sg->dma_length, sg->offset, > > > > page_to_pfn(sg->page)); > > > > > > That is correct, thanks! > > > > > > > hda: DMA table too small > > > > ide dma table, 255 entries, bounce pfn 1310720 > > > > sg0: dma=81c8800, dma_len=4096/0, pfn=1296369 > > > > > > Still the same badness here, it's 2kb into a page so straddles two pages > > > for one entry. > > > > That's normal if it was in the IOMMU and a merged entry. > > > > You can try iommu=nomerge. > > > > Or maybe the higher layers are passing in physically continuous pages > > that get merged? Not too unlikely at boot. > > But that would have to be 1kb or 512b io going in
Yes. Why not?
> , I would expect 4kb to > be the base entries for any normal type of setup (with a 4kb fs). The > 8kb could be one such merged entry, I agree.
Probably yes.
> > > Andi, any idea what is going on here? Why is this throwing up all of a > > > sudden?? > > > > What is throwing up exactly? > > > > There was a change recently in the merging algorithm, but it shouldn't > > cause any bad side effects for correct users of *_map_sg() > > That the request we end up passing to blk_rq_map_sg() and then to > pci_map_sg() ends up with more entries than the driver advertised. So > far I think only Andy reported this, and then only with your > blk_queue_bounce_limit() patch applied.
It shouldn't end up with more, only with less.
Does iommu=nomerge make a difference?
-Andi
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