Any specific reasons why high iowaits are on specific CPUs instead of balanced across all cpus ?

Solution Unverified - Updated -

Issue

This system has 32 processors, in the sar output I can see that only for CPU-15 and CPU-16 IOWAIT is very high , other CPU's are almost idle.

                  CPU     %user     %nice   %system   %iowait    %steal     %idle
19:21:01            0      0.00      0.00      0.00      0.00      0.00    100.00
19:21:01            1      0.00      0.00      0.00      0.00      0.00    100.00
19:21:01            2      0.00      0.00      0.00      0.00      0.00    100.00
19:21:01            3      0.00      0.00      0.00      0.00      0.00    100.00
19:21:01            4      0.00      0.00      0.00      0.00      0.00    100.00
19:21:01            5      0.00      0.00      0.00      0.00      0.00    100.00
19:21:01           15      0.22      0.00      0.22     99.57      0.00      0.00
19:21:01           16      0.22      0.00      0.67     99.12      0.00      0.00

Any specific reasons why high iowaits are on specific CPUs instead of balanced across all cpus ?

Environment

  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6

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