nsysmap.5 (2010 09)

nsysmap(5)

OBSOLETED nsysmap(5)

(Tunable Kernel Parameters)

NAME

nsysmap, nsysmap64 - number of entries in a kernel dynamic memory allocation map

VALUES

Default

8400

Allowed Values

Any positive value.

DESCRIPTION

Note: In HP-UX 11i Version 3, these tunables are no longer present. The system will establish an

initial size for the table, and increase the size as needed. This manual page will be remove in a

future release.

Pre-Release 11i Version 3 Usage

This value sizes the kernel dynamic memory resource map, an array of address/length pairs that describe

the free virtual space in the kernel’s dynamic address space.

This array has historically been statically-sized. That means certain pathological workloads that frag-

ment the kernel address space will result in too many entries for the array. Rather than panicking when

this condition occurs, the system throws away the last entry, which results in "leaked" kernel virtual

address space. If this overﬂow happens often enough, the system eventually runs out of virtual space and

will panic with the following message:

kalloc: out of virtual space.

By making the map size tunable, the system can automatically scale the map size according to the system

workload size and avoid this problem. If the automatic scaling does not work, you can hand-tune to ﬁt a

particular workload. When the default value is overridden, the kernel may increase the value beyond the

your speciﬁcation depending on the system size.

There are different tunables for 32- and 64-bit kernel because the 64-bit kernel has more virtual address

space. The

nsysmap tunable controls 32-bit kernels and the nsysmap64 tunable controls 64-bit ker-

nels.

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 parame-

ter 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://www.hp.com/go/hpux-core-docs

AUTHOR

nsysmap and nsysmap64 were developed by HP.

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nsysmap(5) nsysmap(5) OBSOLETED (Tunable Kernel Parameters) NAME nsysmap, nsysmap64 - number of entries in a kernel dynamic memory allocation map VALUES Default 8400 Allowed Values Any positive value. DESCRIPTION Note: In HP-UX 11i Version 3, these tunables are no longer present. The system will establish an initial size for the table, and increase the size as needed. This manual page will be remove in a future release.
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(Notes) A (Notes) nA 2 Hewlett-Packard Company −1− HP-UX 11i Version 3: September 2010