I'm running a vanilla sarge install on a 2.8GHz P4, booting from a SCSI disk. There's a SATA disk and an IDE. The IDE disk is hda. The motherboard is an Intel 865. When writing a big file to hda, the CPU usage goes to 100% and stays there for a long time. And it takes a lot longer to write to hda than to the others. I interpret that to mean the system is doing programmed I/O instead of DMA. hdparm -i /dev/hda says udma5 (out of a possible 6) is the transfer mode. hdparm /dev/hda says "using_dma = 0 (off)" hdparm -d1 /dev/hda says "setting using_dma to 1 (on) HDIO_SET_DMA failed: Operation not permitted" I've looked at the kernel config and the modules and lsmod. As best I can tell all the IDE code is there -- that definitely doesn't mean it is. I've tried this with a Quantum 20G and a Maxtor 200G with exactly the same results (except the older drive does udma2, max). I googled and went through the tutorial at http://www.linuxdevcenter.com/pub/a/linux/2000/06/29/hdparm.html?page=1 but got nothing like the I/O speed improvements shown there. I got only a 5 or 10 percent improvement. What am I not understanding? -- Glenn English ghe@slsware.com GPG ID: D0D7FF20
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