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HP-UX Reference > K

ksi_send_max(5)

Tunable Kernel Parameters
HP-UX 11i Version 3: February 2007
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NAME

ksi_send_max — limit on number of queued signals per process

VALUES

Default

32

Allowed Values

32 through maxint (0x7fffffff)

DESCRIPTION

ksi_send_max is the per process limit on the number of queued signals that can be posted by a sender and currently pending at receivers. The enforced limit is per process sender based. ksi stands for "kernel signal information" and identifies entries with information about queued signals. There is one per queued signal. Queued signals are used by the sigqueue system call, timer expiration, POSIX real time message queues, and asynchronous I/O. User generated signals (via kill and raise) are not queued.

Who Is Expected to Change This Tunable?

Anyone.

Restrictions on Changing

Changes to this tunable take effect at the next reboot.

When Should the Value of This Tunable Be Raised?

Frequent or heavy use of facilities which use queued signals, may require raising this value. When EAGAIN is returned by the sigqueue system call, the tunable should be raised.

What Are the Side Effects of Raising the Value?

Increased memory usage, but only if used. Every allocated entry is 96 bytes.

When Should the Value of This Tunable Be Lowered?

Only to control the applications' usage of queued signals.

What Are the Side Effects of Lowering the Value?

If too low, failure of applications using queued signals may fail.

What Other Tunable Values Should Be Changed at the Same Time?

ksi_alloc_max to limit the number of queued signals system-wide. Since ksi_alloc_max is per system based and ksi_send_max is per process based, the ksi_alloc_max tunable should always be greater.

Note that the default value for ksi_send_max is 32, and for ksi_alloc_max is 'nproc * 8'.

WARNINGS

All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its meaning changed in future releases of HP-UX.

Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parameter values. After installation, some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tunable values, consult the documentation for the kernel software being installed. For information about optional kernel software that was factory installed on your system, see HP-UX Release Notes at http://docs.hp.com.

AUTHOR

ksi_send_max was developed by HP.

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