projects / people / pmueller / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 00e5a55c BS |
1 | From: Jeremy Higdon <jeremy@sgi.com> |
| 2 | Subject: ia64: sn: fix pci attribute propagation bug | |
| 3 | Patch-mainline: 2.6.29 | |
| 4 | References: bnc#480591 | |
| 5 | ||
| 6 | Customer backups were no longer able to complete within 24 hours after | |
| 7 | upgrading from SLES10 SP1 to SLES10 SP2. Further investigation demonstrated | |
| 8 | tape streaming bandwidth reduced when the scsi controller is operating at PCI | |
| 9 | 66 mhz. Operating both ports simultaneously caused the reduced bandwidth to | |
| 10 | reduce in half to each tape drive. If the controller is operating at PCI-X | |
| 11 | 100mhz, there is no reduction in the tape performance. | |
| 12 | ||
| 13 | Performance degradation is noticeable with a single tape drive writing highly | |
| 14 | compressible data and the controller operating in PCI-66. This only affects | |
| 15 | PCI mode, not PCIx. | |
| 16 | ||
| 17 | kotd SP2 baseline: 4194304000 bytes (4.2 GB) copied, 70.7747 seconds, 59.3 MB/s | |
| 18 | kotd SP1 baseline: 4194304000 bytes (4.2 GB) copied, 26.7403 seconds, 157 MB/s | |
| 19 | ||
| 20 | The culprit patch is: | |
| 21 | patches.fixes/fix-ia64-sn-msi-support | |
| 22 | ||
| 23 | The patch is a backport of the following upstream patch: | |
| 24 | ||
| 25 | http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=83821d3f558dc651e555d62182ed0c95651f41a6 | |
| 26 | ||
| 27 | The fact that the patch is sn2 specific, and that the problem shows up only in | |
| 28 | PCI mode, would easily explain how the performance regression managed to go | |
| 29 | unnoticed for this long. | |
| 30 | ||
| 31 | The problem is that DMA attributes are not getting set on 64bit DMA addresses | |
| 32 | on our PIC ASIC based PCI busses (i.e. O350 and O3000 systems). This only | |
| 33 | affects devices running in PCI mode, not PCIx mode. The result is anything | |
| 34 | from poor performance to data corruption -- so this is a mustfix type problem. | |
| 35 | ||
| 36 | This is a _regression_ in SLES10SP2 introduced _accidentally_ by the patch | |
| 37 | patches.fixes/fix-ia64-sn-msi-support | |
| 38 | That implemented MSI support on IA64 SN2 systems. | |
| 39 | ||
| 40 | The broken code is located in the changes to the pcibr_dmatrans_direct64() | |
| 41 | routine in arch/ia64/sn/pci/pcibr/pcibr_dma.c. | |
| 42 | ||
| 43 | The bug is also present in upstream code which means that SLES11 too suffers | |
| 44 | from the same problem: git commit that introduced the bug is | |
| 45 | 83821d3f558dc651e555d62182ed0c95651f41a6 | |
| 46 | ||
| 47 | This patch resolves the problem. | |
| 48 | ||
| 49 | Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> | |
| 50 | ||
| 51 | ||
| 52 | --- | |
| 53 | arch/ia64/sn/pci/pcibr/pcibr_dma.c | 7 +++---- | |
| 54 | 1 file changed, 3 insertions(+), 4 deletions(-) | |
| 55 | ||
| 56 | --- a/arch/ia64/sn/pci/pcibr/pcibr_dma.c | |
| 57 | +++ b/arch/ia64/sn/pci/pcibr/pcibr_dma.c | |
| 58 | @@ -135,11 +135,10 @@ pcibr_dmatrans_direct64(struct pcidev_in | |
| 59 | if (SN_DMA_ADDRTYPE(dma_flags) == SN_DMA_ADDR_PHYS) | |
| 60 | pci_addr = IS_PIC_SOFT(pcibus_info) ? | |
| 61 | PHYS_TO_DMA(paddr) : | |
| 62 | - PHYS_TO_TIODMA(paddr) | dma_attributes; | |
| 63 | + PHYS_TO_TIODMA(paddr); | |
| 64 | else | |
| 65 | - pci_addr = IS_PIC_SOFT(pcibus_info) ? | |
| 66 | - paddr : | |
| 67 | - paddr | dma_attributes; | |
| 68 | + pci_addr = paddr; | |
| 69 | + pci_addr |= dma_attributes; | |
| 70 | ||
| 71 | /* Handle Bus mode */ | |
| 72 | if (IS_PCIX(pcibus_info)) |