Messages in this thread |  | | Date | Wed, 21 Aug 1996 09:32:18 -0400 | Subject | /proc/stat idle count goes backwards in SMP | From | Lee Hetherington <> |
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When running 2.0.13 SMP, I notice that vmstat's output is ridiculuous for usr/sys/idl when we're effectively using more than one cpu. I've traced this to the idle jiffy count in the first line of /proc/stat. When heavily loaded, the idle count will go *down*. I didn't think that was possible. The usr/sys counts always go up.
Further, the man page for proc says that the idle count should always be 100 times the second value in /proc/uptime. With SMP, the second value is always zero for me. With UP, everything is correct.
What's going on?
Here is a snapshot of the first line of /proc/stat taken every second while I was utilizing both cpus:
cpu 67578 1 779364 6400895 cpu 67605 1 779461 6400881 cpu 67644 1 779552 6400873 cpu 67715 1 779597 6400876 cpu 67746 1 779687 6400864 cpu 67776 1 779773 6400858 cpu 67798 1 779866 6400852
Note that this seems to happen when user+nice+sys > 100%.
Here is a snippet when the system was more or less idle:
cpu 74145 1 795433 6420079 cpu 74145 1 795434 6420189 cpu 74145 1 795435 6420295 cpu 74148 1 795443 6420393
Here is my /proc/uptime:
73129.29 0.00
Lee Hetherington ilh@lcs.mit.edu
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