VP_MEMORY_CACHE_KB configuration parameter
Use the VP_MEMORY_CACHE_KB parameter to create a private memory cache for each CPU virtual processor and tenant virtual processor.
- onconfig.std value
- VP_MEMORY_CACHE_KB 0
- values
0= Off- takes effect
- After you edit your onconfig file and restart the database server.
Usage
Private memory caches can improve performance for memory that is allocated by threads in the HCL OneDB™ server. Private memory caches have no impact on the memory that is allocated to and used by buffer pools or shared memory communication.
When you set the value of the VP_MEMORY_CACHE_KB configuration parameter to a number other than 0, a private memory cache is created for each CPU virtual processor and tenant virtual processor. By default, size of all private memory caches combined is limited to the specified number of KB.
If you want the size of each private memory cache to increase and decrease automatically, as
needed, include a comma and the word DYNAMIC after the size, for example, VP_MEMORY_CACHE_KB
1000,DYNAMIC. Although the maximum initial size of all private memory caches combined cannot exceed
40 percent of the value of the SHMTOTAL configuration parameter, with DYNAMIC mode set, the size of
the caches can expand beyond the initial limit. The total size of the caches cannot exceed the value
of the SHMTOTAL configuration parameter. DYNAMIC mode can improve
performance when many threads are disconnecting at the same time or there is contention for the
shared memory lock. You can use the onstat -g wmx command to display information
about mutexes, such as the shared memory lock mutex shmcb sh_lock, and any threads
waiting on mutexes.
If you reset the VP_MEMORY_CACHE_KB configuration parameter to 0, the memory caches are emptied and disabled.
The onstat -g vpcache command returns statistics about private memory caches.