On Monday 26 June 2006 00:21, Alan Cox wrote: > On Sun, Jun 25, 2006 at 09:32:41PM +0200, Andi Kleen wrote: > > > From a tiny 16MB DMA pool that can't sustain the required load ? Or has that > > > bit changed. > > > > It should be ok because it blocks. It will be slow, but what else do you expect > > from broken hardware like this? > > Sustained 80Mbyte/second I/O rates. At least thats what it gets in other OS > products. This is one of the reasons (broadcomm 4400 was another) that a 30 > or 31 bit DMA zone not a 32bit one was called for, which also didn't happen > it seems. Should we hurt everybody for two terminally broken devices? BCM4400 and its wireless brethen is fine with GFP_DMA btw and mostly only exists in low end machines where most/all of the memory is below 2GB anyways (so the check first approach works quite well) > > The ifdef approach isnt perfect but it essentially means you get good > performance on x86-32 and only x86-64 has problems which seems fine to me, > because its an old card. Blk-bounce would have the same effect. If you set blk-bounce then the block layer will only bounce if the address is < limit and it knows about the different zones on 32bit and will use GFP_NORMAL there. If you have upto 6GB you have a 50:50% chance of not bouncing at least. The ifdef approach is just broken. Please fix it. -Andi - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
