Buffer Cache Parameters

The bufhwm parameter specifies the maximum size for buffer cache memory usage expressed in units of 1K bytes. The default is 2% of physical memory.

UFS File System Parameters

The following table describes the tunable UFS parameters.

Table A-1

Parameter	Description
ufs_ninode	Maximum size of the inode table (default = max_nprocs + 16 + maxusers+ 64)
ncsize	Number of dnlc entries (default = max_nprocs+16+maxusers + 64); dnlc is the directory-name lookup cache.

STREAMS Parameters

The following table describes the tunable STREAMS parameters.

Table A-2

Parameter	Default	Description
nstrpush	9	This is the maximum number of STREAMS pushes allowed.
strmsgsz	0	This is the maximum size for the STREAMS message that a user can create. A value of 0 indicates no upper bound. This parameter may disappear entirely in a future release.
strctlsz	1024	This is the maximum size of the ctl part of a message.
strthresh	0	This is the maximum amount of dynamic memory that the STREAMS subsystem can consume, in bytes. Once this threshold is passed, any pushes, opens, and writes on a STREAMS devices will fail for non-root processes. A value of 0 means no limit.
sadcnt	16	Number of sad devices

Interprocess Communication (IPC) Parameters

The following table describes the tunable interprocess communication parameters.

Table A-3

Parameter	Default	Description
msginfo_msgmap	100	Number of entries in the message map
msginfo_msgmax	2048	Maximum message size
msginfo_msgmnb	4096	Maximum bytes on queue
msginfo_msgmni	50	Number of message queue identifiers
msginfo_msgssz	8	Segment size of a message (should be a multiple of the word size)
msginfo_msgtql	40	Number of system message headers
msginfo_msgseg	1024	Number of message segments (must be < 32768)
seminfo_semmap	10	Number of entries in semaphore map
seminfo_semmni	10	Number of semaphore identifiers
seminfo_semmns	60	Number of semaphores in the system
seminfo_semmnu	30	Number of undo structures in the system
seminfo_semmsl	25	Maximum number of semaphores, per id
seminfo_semopm	10	Maximum number of operations, per semaphore call
seminfo_semume	10	Maximum number of undo entries, per process
seminfo_semvmx	32767	Semaphore maximum value
seminfo_semaem	16384	Maximum value for adjustment on exit
shminfo_shmmax	1048576	Maximum shared memory segment size
shminfo_shmmin	1	Minimum shared memory segment size
shminfo_shmmni	100	Number of shared memory identifiers
shminfo_shmseg	6	Segments, per process

· How to Tune the Message Queue Parameters

* Tune the msgsys parameters using the following syntax:

  set msgsys:msginfo_variable=value

* Tune the semsys parameters using the following syntax:

  set semsys:seminfo_variable=value

* Tune the shmsys parameters using the following syntax:

  set shmsys:shminfo_variable=value

TPI Loopback Pseudo-Driver Parameters

The following table describes the tunable TPI loopback pseudo-driver parameters.

Table A-4

Parameter	Default	Description
tune_t_gpgslo	25	If freemem < t_getpgslow, the system starts to steal pages from processes. If freemem drops below t_gpgslo, the system wakes up the swapper process. The swapper will try to free some memory by swapping processes to disk.
tune_t_fsflush r	30	Rate at which fsflush is run, in seconds
tune_t_minarme m	25	The minimum available resident (not swappable) memory needed to avoid deadlock, in pages
tune_t_minasme m	25	The minimum available swappable memory needed to avoid deadlock, in pages
tune_t_flckrec	512	The maximum number of active frlocks
putbufsz	2000	Size of the putchar buffer
npty	48	Total number of 4.x pseudo-ttys configured
pt_cnt	48	Total number of 5.x pseudo-ttys configured

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Note - Both the freemem and t_gpgslo parameters are defined in pages. Utilities like vmstat translates freemem into bytes from pages.

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· How to Tune the TPI Loopback Pseudo-Driver Parameters

* Tune the tune parameters using the following syntax: set tune:variable=value.

Miscellaneous Parameters

The following table describes a tunable miscellaneous parameter.

Table A-5 Miscellaneous

Parameter	Default	Description
lwp_default_stksize	8192	Size of the kernel stack for lwps. Do not adjust this value unless there is a kernel overflow. The value is expressed in bytes and must be a multiple of PAGESIZE bytes.