I don't know if it is a mainline kernel problem but I can tell you that on
Ubuntu Precise, Linux kernel 3.2 is a disaster for PostgreSQL. I am not even
going to go into a huge rant about it. I am just posting the numbers. See for
yourself. There should be a public service announcement about it.
before upgrade to 3.9
08:35:01 AM CPU %user %nice %system %iowait %steal %idle 08:45:01 AM all 30.91 0.00 5.66 40.05 0.00 23.38 08:55:02 AM all 29.32 0.00 5.10 39.66 0.00 25.92 09:05:02 AM all 31.71 0.00 6.24 40.99 0.00 21.06 09:15:01 AM all 32.45 0.00 6.59 46.74 0.00 14.21 09:25:01 AM all 20.62 0.00 5.39 60.00 0.00 14.00 09:35:01 AM all 31.03 0.00 3.61 33.95 0.00 31.41 09:45:01 AM all 36.54 0.00 3.22 34.13 0.00 26.11 09:55:02 AM all 40.17 0.00 3.66 30.98 0.00 25.19 10:05:01 AM all 33.49 0.00 3.04 32.28 0.00 31.19 10:15:01 AM all 48.63 0.00 2.87 25.50 0.00 23.00 10:25:01 AM all 51.34 0.00 3.56 26.06 0.00 19.04 10:35:01 AM all 39.41 0.00 3.44 29.86 0.00 27.29 10:45:02 AM all 36.07 0.00 8.79 30.94 0.00 24.20 10:55:03 AM all 38.04 0.00 7.98 32.98 0.00 21.01 11:05:11 AM all 39.25 0.00 8.81 36.75 0.00 15.19 11:15:02 AM all 35.19 0.00 8.76 41.98 0.00 14.07 11:25:03 AM all 38.21 0.00 9.65 38.86 0.00 13.28 11:35:02 AM all 42.92 0.00 11.66 34.28 0.00 11.14 11:45:02 AM all 39.40 0.00 9.96 39.03 0.00 11.61 11:55:01 AM all 28.72 0.00 3.27 36.32 0.00 31.69
after upgrade to 3.9
CPU %user %nice %system %iowait %steal %idle
08:35:02 AM all 40.08 0.00 4.46 10.66 0.00 44.80
08:45:01 AM all 38.80 0.00 3.94 7.96 0.00 49.29
08:55:01 AM all 31.48 0.00 3.03 2.58 0.00 62.91
09:05:01 AM all 32.18 0.00 3.09 3.86 0.00 60.87
09:15:01 AM all 26.71 0.00 2.39 3.52 0.00 67.39
09:25:01 AM all 30.49 0.00 3.10 2.80 0.00 63.61
09:35:01 AM all 32.50 0.00 3.49 3.42 0.00 60.60
09:45:01 AM all 36.76 0.00 3.85 6.39 0.00 53.01
09:55:01 AM all 44.45 0.00 4.63 9.23 0.00 41.69
10:05:02 AM all 38.39 0.00 4.28 8.60 0.00 48.72
10:15:01 AM all 33.57 0.00 3.53 4.10 0.00 58.80
10:25:01 AM all 29.42 0.00 2.96 3.16 0.00 64.45
10:35:01 AM all 32.90 0.00 3.37 5.33 0.00 58.40
10:45:01 AM all 34.56 0.00 3.62 4.32 0.00 57.50
10:55:01 AM all 34.84 0.00 3.37 4.27 0.00 57.52
11:05:02 AM all 38.30 0.00 4.05 7.56 0.00 50.08
11:15:01 AM all 36.80 0.00 3.54 9.51 0.00 50.16
11:25:01 AM all 34.79 0.00 3.82 8.17 0.00 53.21
11:35:01 AM all 32.68 0.00 3.07 4.97 0.00 59.28
11:45:02 AM all 31.77 0.00 3.45 6.07 0.00 58.72
11:55:01 AM all 33.58 0.00 3.92 6.39 0.00 56.10