From: George Beshers <gbeshers@redhat.com>
Date: Wed, 22 Apr 2009 10:11:55 -0400
Subject: [ia64] altix: performance degradation in PCI mode
Message-id: 49EF25AB.4000201@redhat.com
O-Subject: [RHEL5.4 PATCH] Performance Degradation in PCI mode: SGI Altix only
Bugzilla: 497136
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Rik van Riel <riel@redhat.com>
RH-Acked-by: Pete Zaitcev <zaitcev@redhat.com>

This is BZ#497136 which pertains only to SGI Altix only.

A customer notice a performance degradation caused by
commit 83821d3f558dc651e555d62182ed0c95651f41a6
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=83821d3f558dc651e555d62182ed0c95651f41a6

The fix is now upstream

commit c63c58056e268b0d6bd6994b69030c144567990d
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c63c58056e268b0d6bd6994b69030c144567990d

The patch has been tested against 2.6.18-140 by me on a
couple of Altix systems.

Please ACK.

diff --git a/arch/ia64/sn/pci/pcibr/pcibr_dma.c b/arch/ia64/sn/pci/pcibr/pcibr_dma.c
index a86c7b9..792e74d 100644
--- a/arch/ia64/sn/pci/pcibr/pcibr_dma.c
+++ b/arch/ia64/sn/pci/pcibr/pcibr_dma.c
@@ -131,11 +131,10 @@ pcibr_dmatrans_direct64(struct pcidev_info * info, u64 paddr,
 	if (SN_DMA_ADDRTYPE(dma_flags) == SN_DMA_ADDR_PHYS)
 		pci_addr = IS_PIC_SOFT(pcibus_info) ?
 				PHYS_TO_DMA(paddr) :
-		    		PHYS_TO_TIODMA(paddr) | dma_attributes;
+				PHYS_TO_TIODMA(paddr);
 	else
-		pci_addr = IS_PIC_SOFT(pcibus_info) ?
-				paddr :
-				paddr | dma_attributes;
+		pci_addr = paddr;
+	pci_addr |= dma_attributes;
 
 	/* Handle Bus mode */
 	if (IS_PCIX(pcibus_info))