On Fri, 01 Jun 2007, Andi Kleen wrote: > Rik van Riel <[EMAIL PROTECTED]> writes: > > > It turns out that the qla2xxx driver sometimes fills up the iotlb > > on purpose and throttles itself when pci_map_sg() fails. In the > > case of a driver that expects and handles pci_map_sg() failures, > > we should not spam the user's console with swiotlb full messages. > > Why does it do that? Could we supply a better interface > for whatever it is trying to do here?
The driver only calls pci_map_sg() once it's insured that all local driver resources are available to submit an I/O to the hardware. > > - printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at " > > - "device %s\n", size, dev ? dev->bus_id : "?"); > > + if (++warnings < 5) > > + printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at " > > + "device %s\n", size, dev ? dev->bus_id : "?"); > > Bad idea imho. swiotlb mappings should always lead to printk by default > because it is pretty dangerous. Why? It's just another resource which is consumed -- the qla2xxx driver is the final consumer before I/O is submitted out on the wire. The mappings are held for the shorted time required -- as such, are released as soon as the I/O completes. > One possible solution for this I could think of would be to define a > new pci_map_sg_couldfail() or similar that doesn't warn and use a weak > fallback just calling pci_map_sg on other IOMMU implementations. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
