· How to List the Kernel Parameters

Display the current kernel parameters values by using the sysdef command.

# sysdef -i * Hostid 53001b80 * * sun4c Configuration * Devices packages (driver not attached) disk-label (driver not attached) deblocker (driver not attached) obp-tftp (driver not attached) . . . * Loadable Objects drv/arp hard link: strmod/arp drv/bpp . . . * System Configuration swap files swapfile dev swaplo blocks free /dev/dsk/c0t1d0s1 32,9 8 205352 205352 * * Tunable Parameters 561152maximum memory allowed in buffer cache (bufhwm) 426maximum number of processes (v.v_proc) 99maximum global priority in sys class (MAXCLSYSPRI) . . . * Utsname Tunables * 5.4 release (REL) minnie node name (NODE) SunOS system name (SYS) prefcs3 version (VER) . . .

· How to Change the Value of a Kernel Parameter

1. Become root.

2. Add a line to the /etc/system file in the form:

   set parameter=value

3. Reboot the system.

   The kernel parses the /etc/system file during autoconfiguration and overrides the default value for the parameters specified in this file.

Example--Changing the Value of a Kernel Parameter

The following line in the /etc/system file sets the value of the max_nprocs to 500 parameter.

set max_nprocs=500

· How to Set the Value of a Kernel Module Variable

1. Become root.

2. Add a line to the /etc/system file in the form:

   set module_name:variable=value

3. Reboot the system.

   The kernel parses the /etc/system file during autoconfiguration and overrides the default value for the parameters specified in this file.

Example--Setting the Value of a Kernel Module Variable

The following line in the /etc/system file sets the value of the msginfo_msgmap parameter in the msgsys module to 150.

set msgsys:msginfo_msgmap=150

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. Use sar(1M) to measure the buffer cache statistics.

UFS File System Parameters

Table 73-1 describes the tunable UFS parameters.

Table 73-1

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

Table 73-2 describes the tunable STREAMS parameters.

Table 73-2

Parameter	Default	Description
nstrpush	9	The maximum number of STREAMS pushes allowed.
strmsgsz	0	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	The maximum size of the ctl part of a message.
strthresh	0	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^(TM)) Parameters

Table 73-3 describes the tunable interprocess communication parameters.

Table 73-3

Parameter Type	Parameter	Default	Description
Message Queue	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)
Semaphore Facility	seminfo_semmap	10	Number of entries in the 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
Shared Memory	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 Interprocess Communication Parameters

1. Become root.

2. Add a line to the /etc/system file using the syntax described in Table 73-4.

Table 73-4

Parameter Type	Parameter	Tuning Syntax
Message Queue	msgsys	set msgsys:msginfo_variable=value
Semaphore Facility	semsys	set semsys:seminfo_variable=value
Shared Memory	shmsys	set shmsys:shminfo_variable=value

3. Reboot the system.

   The kernel parses the /etc/system file during autoconfiguration and overrides the default value for the parameters specified in this file.

Memory Management Parameters

Table 73-5 describes the tunable memory management parameters.

Table 73-5

Parameter	Default	Description
lotsfree	scaled based on physical memory	If freemem drops below lotsfree, the system starts to steal pages from processes.
tune_t_fsflushr	30	Rate at which fsflush is run, in seconds
tune_t_minarmem	25	The minimum available resident (not swappable) memory needed to avoid deadlock, in pages
tune_t_minasmem	25	The minimum available swappable memory needed to avoid deadlock, in pages
tune_t_flckrec	512	The maximum number of active frlocks

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Note - Since the Solaris 2.4 release, the tune_t_gpgslo parameter has been replaced by a more complicated criteria for swapping based on the number of runnable threads. More information on this new criteria will be available for the Solaris 2.5 FCS release.

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The freemem parameter is defined in pages. Utilities like vmstat translates freemem into bytes from pages.

· How to Tune Memory Management Parameters

1. Become root.

2. Add a line to the /etc/system file using the following syntax.

set tune:variable=value

3. Reboot the system.

   The kernel parses the /etc/system file during autoconfiguration and overrides the default value for the parameters specified in this file.

Miscellaneous Parameters

Table 73-6 describes tunable miscellaneous parameters.

Table 73-6

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.
npty	48	Total number of 4.x pseudo-ttys configured
pt_cnt	48	Total number of 5.x pseudo-ttys configured

· How to Tune Miscellaneous Parameters

1. Become root.

2. Add a line to the /etc/system file using the following syntax.

   set parameter=value

3. Reboot the system.

   If you changed device related kernel parameters, you need to use the -r option when booting the system. When the system boots, the kernel parses the /etc/system file during autoconfiguration and overrides the default value for the parameters specified in this file.

Example--Tuning Miscellaneous Parameters

The following line in the /etc/system file sets the value of the pt_cnt parameter to 200.

set pt_cnt=200