Some load or query performance issues may be traced to lock contention. To find out if lock contention may be affecting performance on your system, use the facilities provided by IQ or your operating system:
Run the IQ monitor with the -contention option.
On UNIX platforms, run the sar or vmstat utility.
On Windows platforms, check the CPU usage in the Task Manager.
If your kernel system time is greater than 10%, you may be experiencing lock contention.
Sybase IQ limits lock contention by partitioning your IQ main and temporary caches. The default level of partitioning is based on the number of CPUs on your IQ server, and should be adequate under most conditions. If you suspect lock contention, you may find it useful to control the level of partitioning directly by setting either the -iqpartition server startup option or the Cache_Partitions database set option. To set these options, see “Using command-line options” and “CACHE_PARTITIONS option” in the Sybase IQ Reference Manual.
Higher than normal kernel system time can also indicate
that your kernel is not well tuned. If this is the case, you probably
need to adjust kernel parameters; changing IQ settings will not
overcome an improperly tuned kernel.
For an example of managing write lock contention on a table, see “Managing write lock contention on a table” in Chapter 1, “Troubleshooting Hints” of the Sybase IQ Troubleshooting and Error Messages Guide.
