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Richard Freeman <rich@××××××××××××××.net> posted |
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46B33881.2060801@××××××××××××××.net, excerpted below, on Fri, 03 Aug 2007 |
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10:15:29 -0400: |
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> Actually, as long as you have enough swap your RAM doesn't really |
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> matter. In the worst case it just swaps to disk, which is what it would |
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> be doing anyway if you didn't have a tmpfs. Even if only 10% of the |
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> short-lived files didn't make it to disk it would be a huge savings in |
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> IO waits. |
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Thanks for pointing that out, yes. |
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> Also, consider using ionice (from schedutils I think) - it lets you |
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> schedule IO the way nice schedules CPU. It can have a big impact if you |
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> have a lot of disk churn. |
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It can. However, with the proper i/o scheduler (CFQ), plain nice is |
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often good enough, since the i/o scheduler implements logical defaults |
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based on nice value -- higher nice means higher default ionice. |
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That did get me to switch i/o schedulers here, BTW. I had been using |
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anticipatory until I setup the RAID, at which point I switched to the |
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simpler deadline, since anticipatory does its anticipation stuff assuming |
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a single spindle. After reading a bit about the workings of ionice |
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however, and how CFQ defaults i/o priority based on CPU timeslice |
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priority (and therefore nice), I switched to it. With the memory I have, |
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most disk access after the initial is cached, so it didn't affect me a |
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lot, and RAID helps in that regard as well, but it did seem to make some |
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difference. |
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So anyway, I'm in pretty strong agreement with you. =8^) |
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-- |
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Duncan - List replies preferred. No HTML msgs. |
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"Every nonfree program has a lord, a master -- |
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and if you use the program, he is your master." Richard Stallman |
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-- |
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