vmstat:
those high "in" and "cs" value .. i know what they are ..
in --> Number of interrupts received by the system per second
cs --> Rate of context switching in the process space (in number/sec)
but what they do, is this is the thing that is affecting my system?? .....
---------- Post updated at 06:11 AM ---------- Previous update was at 05:49 AM ----------
I found something::
in: The number of interrupts per second, including the clock.
cs: The number of context switches per second.
(A context switch occurs when the currently running thread is different from the previously running thread, so it is taken off of the CPU.)
It is not uncommon to see the context switch rate be approximately the same as device interrupt rate (in column)
If cs is high, it may indicate too much process switching is occurring, thus using memory inefficiently.
If cs is higher then sy, system is doing more context switching than actual work.
High r with high cs -> possible lock contention
Lock contention occurs whenever one process or thread attempts to acquire a lock held by another process or thread. The more granular the available locks, the less likely one process/thread will request a lock held by the other. (For example, locking a row rather than the entire table, or locking a cell rather than the entire row.)
When you are seeing blocked processes or high values on waiting on I/O (wa), it usually signifies either real I/O issues where you are waiting for file accesses or an I/O condition associated with paging due to a lack of memory on your system.
but still not able to understand the lock contention part and what should I do to resolve this issue. ??
You've got a series of issues, it looks like. You have several RT processes, those preempt everybody else. This is not necessarily always bad.
One problem appears to be context switching, often caused when nobody except high priority processes completes a quantum. Or there are loads of low priority processes that get the cpu frequently due to schedule policy and then get booted out.
During context switches, unless there is cpu affinity for the processes playing musical chairs, every context switch potentially involves cache latency. So you MAY get lots of cpu cache thrashing. Even with cpu affinity set you can get thrashing.
This is not so bad when a process gets a full 20ms (example value) quantum. It is murder when most processes get kicked out after 1ms. Because relatively much more cpu time is spent on loading cpu caches, not running the codestream.
IMO the large cpu wait queues speak to that.
Q: what exact OS are you running? and exact CPU's (NUMA?)
Q: what does this server do aside from run ruby, java and nfs?
Q: what is the output of uptime ( or who -r)
Q: can you run sar (set it up to gather data?). We can help
OS >> Red Hat Enterprise Linux Server release 5.7 (Tikanga)
CPUs >> 4
other than ruby,Java and nfs >> EAI
uptime >> 17:44:30 up 51 days, 2:09, 10 users, load average: 7.13, 8.11, 8.65
sar:
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