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Ryan Detzel
Asked: 2011-04-22 04:23:11 +0800 CST

Load high with very little CPU usage?

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The load has been sitting at around 6 but there is very little running on the box. Any ideas what's causing this? It's a large AWS instance.

CPU Load

procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 0  4      0 4815700 179440 548200    0    0     0     3    2    3  5  1 91  0
 0  4      0 4821256 179444 548192    0    0     0     0  228  373  1  1 48 48
 0  4      0 4821296 179444 548196    0    0     0     0   96  150  0  0 50 50
 0  4      0 4822832 179444 548200    0    0     0     0  158  197  1  1 49 49
 0  4      0 4823452 179444 548200    0    0     0     0   98  149  0  0 50 50
 0  4      0 4823452 179444 548200    0    0     0     0   94  149  0  0 50 50
cpu-usage load-average

2 Answers

  1. As noted by James C, it looks like you are having trouble with disk IO, not CPU time. If your instance is in the us-east data center they are having trouble there today and latency to EBS volumes is way up.

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  2. The right most column in the vmstat output indicates that there's a lot of i/o wait going on. 50% of CPU time. Could you please post the output of iostat 10 6 as this should give us a good insight as to which disks are slowing stuff down.

    I'm not sure what EBS performance is like but if you're doing a lot of I/O then it might be having problems keeping up.

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