On Nov 9, 2007 10:04 AM, Tony Battersby <tonyb@xxxxxxxxxxxxxxx> wrote: > The 3ware 9500S-8 SATA RAID controller exhibits terrible write > performance when PCI memory-write-and-invalidate is disabled. This is > easy to demonstrate by replacing pci_try_set_mwi() in the patch below > with pci_clear_mwi(). My benchmarks show the following: > > MWI disabled: 15 MB/s write, 330 MB/s read > MWI enabled: 240 MB/s write, 330 MB/s read > > Most motherboards will enable MWI without the driver having to set it > explicitly, so most people probably wouldn't encounter this problem. > For the few motherboards that don't enable it, this patch could give a > 16x performance improvement for writing. > > This issue does not seem to affect the 9550SX controller, but the patch > doesn't hurt it either. I haven't tested any of the other 3ware > controllers. > > Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx> > --- > --- linux-2.6.24-rc2/drivers/scsi/3w-9xxx.c.orig 2007-11-09 12:32:32.000000000 -0500 > +++ linux-2.6.24-rc2/drivers/scsi/3w-9xxx.c 2007-11-09 12:33:20.000000000 -0500 > @@ -2010,6 +2010,7 @@ static int __devinit twa_probe(struct pc > } > > pci_set_master(pdev); > + pci_try_set_mwi(pdev); > > if (pci_set_dma_mask(pdev, DMA_64BIT_MASK) > || pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK)) > > > - > To unsubscribe from this list: 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 > ACK... -Adam - To unsubscribe from this list: 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
