Commit:     1e6c38cec08f88b0df88a34e80f15492cace74e9
Parent:     8ee24023ef43c77cdaea1add00e1e45cc4fc3261
Author:     Tony Battersby <[EMAIL PROTECTED]>
AuthorDate: Fri Nov 9 13:04:35 2007 -0500
Committer:  James Bottomley <[EMAIL PROTECTED]>
CommitDate: Fri Jan 11 18:22:42 2008 -0600

    [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
    Signed-off-by: Tony Battersby <[EMAIL PROTECTED]>
    Acked-by: adam radford <[EMAIL PROTECTED]>
    Signed-off-by: James Bottomley <[EMAIL PROTECTED]>
 drivers/scsi/3w-9xxx.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index afb262b..1c24483 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_try_set_mwi(pdev);
        if (pci_set_dma_mask(pdev, DMA_64BIT_MASK)
            || pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK))
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