I've noticed a possible problem in Linux 2.2.18 relating to a CD-R drive connected to the secondary ide port. I'm not certain whether the problem cause is in the kernel software, in the hardware, or in a combination thereof. Although I've found a way to bypass the problem, I'm including a description here for anyone who wishes to better document the issue or create a more robust kernel. While the IDE CD-R drive works perfectly in and of itself, continuous access to the drive degrades the operation of other system tasks. Pointer movement with XFree86 4.0.1 or gpm becomes noticeably choppy, MIDI music playback under the ALSA drivers (0.5.10) progresses in slow motion, and network access through an external modem connected to a serial port all but ceases to function. Additional investigation also revealed that the system's notion of time slows down. For example, during continuous read access from the IDE CD-R drive, a 55 second piece of MIDI music is stretched out to nearly a minute and a half. While "time" consistently reports about 57 elapsed real seconds, manually timing the MIDI playback yielded the following repeatable results at various processor speeds: 500 MHz: 86 seconds 650 MHz: 85 seconds 750 MHz: 83 seconds Likewise, repeated application of "date" shows that system time progresses slower than real time. With no CD-R access, "time" reports about 55 elapsed real seconds for the 55 second MIDI playback test, and a stopwatch confirms this time. System time as reported by "date" also advances correctly. The problem appears whether using the CD-R drive for continuous reading (at ~3 MB per second) or writing (at ~600 KB per second). Trying "ide-cd" for read access instead of "ide-scsi" shows the same problem. The CD-R drive is wired as the master on the secondary IDE port, with an ATAPI Zip drive wired as the slave, with nothing connected to the primary IDE port. Access to the Zip drive (continuous read at ~700 KB per second) does not cause the problem, and removing the Zip drive from the system does not offer a remedy. All SCSI drives accessed through the Symbios 8751 SCSI adapter work fine with no side effects. The problem disappears when the wiring for the CD-R drive is switched from the secondary IDE port to the primary IDE port. The compiler version used to build the 2.2.18 kernel reads: gcc version 2.95.2 20000220 (Debian GNU/Linux) Double checking by building the same kernel with gcc version 2.7.2.3 again demonstrates the same behavior. Mainboard/Processor: ABit KT7 / 650 MHz Athlon (model 4) "cat /usr/src/linux/.config | grep IDE | grep =": CONFIG_BLK_DEV_IDE=y CONFIG_BLK_DEV_IDEDISK=y CONFIG_BLK_DEV_IDESCSI=y CONFIG_BLK_DEV_IDEPCI=y CONFIG_BLK_DEV_IDEDMA=y CONFIG_IDEDMA_AUTO=y CONFIG_PARIDE_PARPORT=y CONFIG_VIDEO_DEV=m CONFIG_VIDEO_SELECT=y CONFIG_VIDEO_SELECT=y "cat /proc/scsi/scsi": Attached devices: Host: scsi0 Channel: 00 Id: 00 Lun: 00 Vendor: FUJITSU Model: MAB3045SC Rev: 0108 Type: Direct-Access ANSI SCSI revision: 02 Host: scsi0 Channel: 00 Id: 01 Lun: 00 Vendor: FUJITSU Model: MAB3045SC Rev: 0108 Type: Direct-Access ANSI SCSI revision: 02 Host: scsi0 Channel: 00 Id: 03 Lun: 00 Vendor: PLEXTOR Model: CD-ROM PX-20TS Rev: 1.00 Type: CD-ROM ANSI SCSI revision: 02 Host: scsi1 Channel: 00 Id: 00 Lun: 00 Vendor: IOMEGA Model: ZIP 100 Rev: 24.D Type: Direct-Access ANSI SCSI revision: ffffffff Host: scsi1 Channel: 00 Id: 01 Lun: 00 Vendor: PLEXTOR Model: CD-R PX-W8432T Rev: 1.07 Type: CD-ROM ANSI SCSI revision: 02 Regards, - John - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
