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HP-UX Reference > Nnproc(5)Tunable Kernel ParametersHP-UX 11i Version 2: December 2007 Update |
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NAMEnproc — limits the number of processes allowed to exist simultaneously VALUESDESCRIPTIONThe nproc tunable controls the absolute number of processes allowed on a system at any given time. Increasing it will allow more processes, and lowering it will restrict the number of processes. It can be determined that nproc is too low when the proc: table is full message is seen in the message buffer. The message buffer can be read via dmesg or syslog. This message indicates that an application was unable to create a new process. Setting nproc too low can cause application failures due to an inability to fork new processes. It can be determined how many processes have been used simultaneously by calling pstat_dynamic and examining the psd_numprocsallocd. This field indicates the "high water" mark of the number of processes that have been simultaneously used. When Should the Value of This Tunable Be Raised?The tunable should be increased when running large numbers of processes simultaneously. When Should the Value of This Tunable Be Lowered?The value should be lowered only to limit the number of processes on the system, or when there is memory pressure and the value of nproc is far above the expected usage. What are the Side Effects of Lowering the Value?Increased risk of application failure due to the inability to fork new processes. What Other Tunable Values Should Be Changed at the Same Time?Increase nkthread to ensure there are sufficient threads for each process. nfile and ninode should be increased (and are not by default) to allow applications to manipulate files. ksi_alloc_max should be adjusted, as the default formula is multiple of nproc. A single user may not consume all processes on the system (see maxuprc). Some of these other tunables used to adjust automatically with changes in nproc. These adjustments must now be made explicitly. Other tunables may require a reboot to take effect. So, dramatic increases in nproc without reboot should be made with caution. WARNINGSAll 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. |
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