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Swapping itself has the usefulness of handling applications or data files larger than main memory, but in systems where a long-term resident application such as DBMS are operated, the disk I/O delay of the operating system layer due to swapping since the response time of the DBMS may be irregular or delayed with time, . So file cache is a consideration factor depending on the system use.


The default memory manager of AIX is to convert unused memory areas to file cache as much as possible.

In this state, if an additional memory allocation request requso if the system does noest occurs and the there is insufficient free memory is insufficient at the moment, the process allocates the swapped-out area in swaps out the memory being used or file cache the area that is not easily accessedoften accessed from the file cache area, and then allocates it.

At this time, when a transaction approaching the swapped out area occurs, the performance is not uniform.


In the case of AIX, some of the resource limit items are set through the following kernel parameter changes, not the user configuration file setting using ulimit, which is commonly useduand the soft-limit means that the hard-limit can sed.

Altibase is a single-process, multi-thread-based application program, so if the system does not have an application program specifically running outside of any application programs other than Altibase, there is no need to specifically consider the number of process limits per user. In  In some cases, it may be necessary to appropriately expand the limit on the number of processes per user by predicting the number.


Resource limit values are divided into the concept of hard-limit and soft-limit. The hard-limit means the maximum value of kernel-level resource limit that cannot be changed except the system administrator account (root), and the soft-limit means that the current user account can change up to the hard-limit can be changed within the current user account (refer to the ulimit -S/-H option for details.)

The soft-limit is effective while the user maintains a session by accessing it, and changes are immediately reflected. However, when other sessions of the same user account are connected, the existing soft-limit is reflected, so the ulimit command is often added to the user account configuration file.

However, this method may not be intended due to the global hard-limit, so it is recommended to systematically apply it through editing system-wide resource configuration files rather than applying user account units using environment configuration files.


Separate environment variables need to be set for Altibase, a multi-thread based application program. For reference, this document mentions only representative ones, but it should be noted that all environment variables related to multi-threads supported by AIX need to be considered.

The following items can run Altibase without setting the are recommended environment variables in order to prevent performance degradation in a multi-threaded SMP system, but since it can cause failure due to unknown reasons, it must be setsystems.Altibase can be operated without setting the environment variable, but must be set because failures may occur due to unknown causes.

 Sets to remove.
Environment VariableDescription
AIXTHREAD_MNRATIOThe number of k kernel threads for processing n user threads
AIXTHREAD_SCOPESets the thread model to 1:1
AIXTHREAD_MUTEX_DEBUGThe mutex and condition variables being used by the pthread library, The overhead of the
Set to remove the overhead  of the pthread library due to the mutex / condition variable in use / read/write lock management used by the debugger.
AIXTHREAD_RWLOCK_DEBUGThe mutex and condition variables being used by the pthread library, The overhead of the read/write lock used by the debugger. Sets to remove.
AIXTHREAD_COND_DEBUGThe mutex and condition variables being used by the pthread library, The overhead of the read/write lock used by the debugger. Sets to remove.
SPINLOOPTIMEThe number of attempts to acquire a lock in the state of CPU resource acquisition
YIELDLOOPTIMEThe number of times to yield CPU resources while holding lock
MALLOCMULTIHEAPSets up in a multi-threaded environment that uses a lot of malloc
AIXTHREAD_MUTEX_FASTAs This is an option to change the operating system's internal mutex_locking behavior. If the operation method of the operating system. If mutex_contention is severe, set it to ON to improve the performance.  Can be represented. It is provided in AIX 5.2 and later.


Code Block
-bash-3.2$ instfix -i | grep IV28577
All filesets for IV28577 were found.

If there is no patch, it is recommended that an AIX engineer perform a patch or upgrade because no return value appearsno value is displayed. It is recommended to perform patch or upgrade through AIX engineer.

In addition, it is recommended to apply the latest patch to avoid various problems known in AIX.