Activity Summary

The Activity Summary window gives a quick access to the activity of a Informix database. 

Sessions

Active Number of sessions which are currently active
Idle Number of sessions which are currently inactive
Waiting Number of sessions waiting on resources

CPU (%)

User percentage of user cpu consumed
System percentage of system cpu consumed

Cache hit ratio (%)

Indicates how effectively the Informix database is using memory cache. Both read and write cache rates should be in the 80 to 90th percentile. Low rates indicate Informix is doing a lot more disk reads and writes than it should. If the values are lower than 80%, you need to consider increasing the value of the BUFFERS paramter in your Informix Configuration file to achieve higher read and write cache rates.

Read Read cache rate
Write Write cache rate

Rollback ratio (%)

Percentage of transactions rolled-back. if the percentage of transactions rolled-back starts to increase sharply, there may be a lot of errors or deadlocks occuring in the system.

Checkpoints /s

Number of checkpoints per second. A checkpoint is the process of synchronizing pages on disk with pages in the shared memory buffer pool. During checkpoints, Informix server prevents user threads form entering critical session and blocks all transaction activities. Thus, if checkpoint duration is long, users may experience system hanging. This is especially true in OLTP environments where there are thousands of transactions and the response time is most critical.

If this is high, the physical or logical logs might be too small ot the checkpoint interval might be too short.


Disk sort ratio (%)

This ratio records the proportion of sorts that were too large to be completed in memory. The higher is the percentage, the more efficient are your sort operations.

Sequential scans /s

Indicates how many sequential scans have been performed per second.If this number is large, it may indicate some performance problems, especially if the system is in OLTP environment. You then need to do some more further investigations to find out the root cause of excessive sequential scans.

Waits /s

Latch Number of times a thread waited for a shared memory resource per second.
Lock Number of times a thread waited on a lock per second.
Checkpoint Number of checkpoint waits per second.
Buffer Number of times a thread waited for a buffer per second. This might indicate too few LRUs, a number of hot pages or a transaction holding a buffer too long.

 

See also:

 





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