Messages in this thread | | | Date | Sat, 22 Nov 2003 14:48:28 -0600 | From | Chris Cheney <> | Subject | bugme #1217: "Use PCI DMA by default when available" does not work |
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I sent the following followup report to the bug I filed at bugme.osdl.org several months ago about my hpt372 ide controller being slow.
I have determined what causes the dramatic slowdown problem. It is not drive specific but it may be specific to the hpt controllers. The problem is due to using automatic dma. If I don't have the following two options set in my kernel then it runs at full speed when I turn on dma with hdparm. Otherwise using automatic dma I get somewhere between a 50% - 700% slowdown on writes, reads seem to not be as badly affected. This is reproducible on both 2.4.23-rc1-xfs and 2.6.0-test9-bk24 (the two I tested on).
CONFIG_IDEDMA_PCI_AUTO=3Dy=20 CONFIG_IDEDMA_AUTO=3Dy=20
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