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I discovered yesterday that the 2.2 kernels are set up not to use DMA to drive your disks by default. When I upgrade, one of the first things I do is to customize the kernel. There are several performance issues. One is to compile as a Pentium II. Another is to use hardware floating point rather than software emulation. I had some disk problems over the weekend (not Linux related), and I discussed them with my office mate. He mentioned the DMA issue. I first looked at the boot log, which didn't raise any flags. I then looked at the kernel config, and found a flag "Use DMA by default" in the block drivers section. My wording might a bit off. Turning this flag on causes the kernel to use DMA by default. When looking at the boot log, you should see DMA or UDMA adjacent to the drives. I think this applies only to IDE. I think SCSI uses DMA by default. -- Jerry Feldman (HP On-Site Consultant) http://gbrweb.msd.ray.com/~gzf/ +-------------------------------------------------------+-----Note: ------+ | Raytheon Electronic Systems (W) (781)999-1837/1-1837 | My views may not| | Mail Stop: S3SG10 (F) (781)999-4030/1-4030 | reflect the | | 180 Hartwell Road (W) gzf at gbr.msd.ray.com | views of my | | Bedford, MA 01730-2498 (FWD:H+W) gaf at blu.org | employer. | +-------------------------------------------------------+-----------------+ - Subcription/unsubscription/info requests: send e-mail with "subscribe", "unsubscribe", or "info" on the first line of the message body to discuss-request at blu.org (Subject line is ignored).
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