From 1e6c38cec08f88b0df88a34e80f15492cace74e9 Mon Sep 17 00:00:00 2001 From: Tony Battersby <tonyb@cybernetics.com> Date: Fri, 9 Nov 2007 13:04:35 -0500 Subject: [PATCH] [SCSI] 3w-9xxx: fix abysmal write performance on some motherboards 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@cybernetics.com> Acked-by: adam radford <aradford@gmail.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> --- drivers/scsi/3w-9xxx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c index afb262b4be15b8..1c244832c6c8aa 100644 --- a/drivers/scsi/3w-9xxx.c +++ b/drivers/scsi/3w-9xxx.c @@ -2010,6 +2010,7 @@ static int __devinit twa_probe(struct pci_dev *pdev, const struct pci_device_id } 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)) -- GitLab