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Full Discussion: Causes of high runq-sz and cswch/s output from sar
Top Forums UNIX for Advanced & Expert Users Causes of high runq-sz and cswch/s output from sar Post 302241726 by fulat2k on Tuesday 30th of September 2008 04:53:41 AM
Old 09-30-2008
Question Causes of high runq-sz and cswch/s output from sar
Hi folks,

I'm running RHEL4 (2.6.9 - 64 bit) on a 4 CPU Dual Core Xeon. This server is running DB2 database. I've been getting the following readings from sar over the past week:

Code:
09:35:01 AM   cswch/s
09:40:01 AM   4774.95
09:45:01 AM  27342.76
09:50:02 AM 196015.02
09:55:01 AM 337021.92
10:00:01 AM 347007.79
10:05:01 AM 309210.99
10:10:01 AM 308174.09
10:15:01 AM 350074.07
10:20:01 AM 350716.36
10:25:01 AM 329279.95
10:30:02 AM 319551.01
10:35:01 AM 312952.02
10:40:01 AM 130142.16
10:45:01 AM   6056.06
10:50:01 AM   5131.25

Code:
09:35:01 AM   runq-sz  plist-sz   ldavg-1   ldavg-5  ldavg-15
09:40:01 AM         5      1156      7.31      6.63      6.69
09:45:01 AM        29      1190     29.53     15.30      9.89
09:50:02 AM        45      1298     58.97     39.22     21.26
09:55:01 AM       117      1323     85.29     67.64     38.24
10:00:01 AM        71      1332     70.71     76.38     50.85
10:05:01 AM        96      1286     58.03     65.37     53.27
10:10:01 AM       105      1316     77.59     70.25     58.42
10:15:01 AM       136      1334     97.88     82.74     66.72
10:20:01 AM        70      1308     80.77     84.55     72.34
10:25:01 AM        86      1308     77.55     81.79     74.77
10:30:02 AM       177      1327    121.49    100.03     83.81
10:35:01 AM        95      1334    135.49    118.93     95.86
10:40:01 AM        10      1212     14.40     71.86     84.11

The context switching and run queue length values stick out like a sore thumb. However, the CPU load at that time is normal although slightly alleviated:

Code:
09:40:01 AM       all     58.65      0.00      1.81      0.16     39.38
09:45:01 AM       all     72.99      0.00      2.44      0.27     24.30
09:50:02 AM       all     53.78      0.00      6.21      1.19     38.82
09:55:01 AM       all     45.99      0.00      9.12      0.75     44.14
10:00:01 AM       all     46.96      0.00      9.25      0.76     43.02
10:05:01 AM       all     42.43      0.00      9.36      2.05     46.16
10:10:01 AM       all     47.45      0.00      8.60      0.38     43.56
10:15:01 AM       all     45.64      0.00      9.17      0.34     44.84
10:20:01 AM       all     44.27      0.00      8.69      0.62     46.43
10:25:01 AM       all     45.23      0.00      9.04      0.73     45.00
10:30:02 AM       all     57.97      0.00      9.27      0.08     32.68
10:35:01 AM       all     61.81      0.00      9.62      0.09     28.48
10:40:01 AM       all     66.45      0.00      6.24      0.21     27.11
10:45:01 AM       all     45.15      0.00      2.41      0.28     52.16
10:50:01 AM       all     33.64      0.00      2.05      0.23     64.08
10:55:01 AM       all     39.24      0.00      3.27      0.27     57.22
11:00:01 AM       all     49.34      0.00      4.09      0.22     46.35
11:05:01 AM       all     42.20      0.00      2.45      0.32     55.02
11:10:01 AM       all     35.33      0.00      2.14      0.20     62.33
11:15:01 AM       all     33.07      0.00      2.31      0.24     64.38
11:20:01 AM       all     35.54      0.00      4.20      0.21     60.05
11:25:01 AM       all     34.20      0.00      2.02      0.16     63.61
11:30:01 AM       all     31.26      0.00      1.79      0.17     66.78
11:35:01 AM       all     36.21      0.00      2.88      0.14     60.76

I've checked on any long running queries, but there seems to be none. My question is how can I find the cause of the high system usage? Is it possible to pinpoint the process(es) which is causing the issue?


Thanks!
 

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