Messages in this thread | | | Date | Sun, 9 Dec 2001 18:36:52 -0500 | From | Tom Vier <> | Subject | block devs and high latency |
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while doing some experimentation, i've discovered an annoying problem. when writing to one or two scsi drives, there seems to be some weird side effects. the effect is the same, whether i run cat /dev/zero > /dev/sdc1 or dd bs=131027 if=/dev/zero of=/dev/sdc1. buffer size doesn't make a difference, bs can also be set to 5 megs. if you hit ctrl-c to kill one or two of the dd or cat procs, you can't switch consoles for a good 20-30 seconds (my estimation). i was running screen and i couldn't switch screens, either, so, at some level, all keyboard input was being delayed. the machine has normal ping times during this.
also, if you run sync while the other procs are running, it won't return until they're done. it also is unkillable during this, in state D. is this a race? ie, as sync flushes dirty buffers, they're added just as fast. i always thought sync was atomic and meant "flush every io issued before this call, but not after".
this is using 2.4.17-pre6 on an alpha pws500 with a half gig of ram, and a sym53c895 (using the new driver).
-- Tom Vier <tmv5@home.com> DSA Key id 0x27371A2C - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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