On Thu, 2007-08-02 at 14:28 -0600, Zan Lynx wrote: > On my laptop while running heavy disk read/write loads, I have > discovered that the deadline IO scheduler gives me a much better "feel" > and much shorter (and fewer) system freezes. This is as compared to the > CFQ scheduler. Something else I found today. I'm back to the CFQ scheduler. Deadline was better in the heavy write-out situation, but not so good at reading. It appears nr_requests was too low at the default of 128. I have bumped it to 1024. Watching iostat's avgqu-sz field during writeout, I see it hit over 450 now. Pauses in things like music playback are much reduced. My theory is that an atom writeout stalls and blocks read requests if it can't stuff the whole thing into the disk queue. If that's true, it'd almost be nice to have a printk "stall warning" or just have Reiser4 shove nr_requests up automatically until the queue can hold a complete atom write. I'm probably wrong with my theory, but I hope the nr_requests suggestion can help other's with lag problems. -- Zan Lynx <zlynx@xxxxxxx>
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