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authorTony Battersby <tonyb@cybernetics.com>2007-11-09 21:04:35 +0300
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2008-01-12 03:22:42 +0300
commit1e6c38cec08f88b0df88a34e80f15492cace74e9 (patch)
tree9d477b95a05f9a4552da19429da0265878d7deba
parent8ee24023ef43c77cdaea1add00e1e45cc4fc3261 (diff)
downloadlinux-1e6c38cec08f88b0df88a34e80f15492cace74e9.tar.xz
[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>
-rw-r--r--drivers/scsi/3w-9xxx.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index afb262b4be15..1c244832c6c8 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))