Monitoring Memory Use

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Monitoring Memory Use

For information about using monitoring information to tune memory, see Tuning Memory Allocation. View memory-use information from ISA or execute the following onstat commands.

onstat -g Option	Description
xctl onstat -g ffr pool name \| session id	Lists free fragments for a pool of shared memory.
xctl onstat -g mem pool name \| session id	Displays memory statistics for the pools associated with a session. If you do not provide an argument, this option displays pool information for all sessions.
xctl onstat -g nsc client id	Displays shared-memory status by client ID. If you omit client id, this option displays all client status areas.
xctl onstat -g nsd	Displays network shared-memory data for poll threads.
xctl onstat -g nss session id	Displays network shared-memory status by session ID. If you omit session id, this option displays all session status areas.
xctl onstat -g seg	Displays shared-memory segment statistics. This option shows the number and size of all attached segments.
xctl onstat -g ufr pool name \| session id	Displays allocated pool fragments by user or session.

Monitoring Buffer and Cache Rates

For information about tuning memory buffer size for improved read-cache rates, see Tuning BUFFERS to Improve the Read-Cache Rate.

onstat -g Option: Description
xctl onstat -p: Displays read-cache information.
xctl onstat -g dic table name: Displays one line of information for each table that is cached in the shared-memory dictionary.
xctl onstat -g iob: Displays large private buffer use by I/O virtual-processor class.
If you enter a specific table name as a parameter, this option displays internal SQL information about that table, including constraints and index descriptors and fragments.

Monitoring the LRU Queues and Page Cleaning

For information about using LRU monitoring information to tune the write-cache rate, see Tuning Write-Cache Rates.

onstat Option: Description
xctl onstat -R: Displays each LRU queue number and type and the total number of queued and dirty buffers.
For the performance implications of LRU queue statistics, see Specifying the Number of Least Recently Used Queues.
xctl onstat -F: Displays page-cleaning statistics that include the number of chunk, LRU, and foreground writes.

Monitoring Threads

View thread information from ISA or execute the following onstat command options.

onstat -g Option

Description

xctl onstat -g act

Lists active threads.

xctl onstat -g ath

Lists all threads.

The sqlexec threads represent portions of client sessions; the rstcb value corresponds to the user field that the onstat -u command displays.

For more information and sample output, see Monitoring User Threads and Transactions.

xctl onstat -g rea

Lists ready threads.

xctl onstat -g sle

Lists all sleeping threads.

xctl onstat -g sts

Lists maximum and current stack use per thread.

xctl onstat -g tpf tid

Displays a thread profile for tid.

If you omit the tid, this argument displays profiles for all threads.