nsysmap(5)nsysmap(5)NAME
nsysmap, nsysmap64 - number of entries in a kernel dynamic memory allo‐
cation map
VALUES
Default
8400
Allowed Values
DESCRIPTION
Note: In HP-UX 11i Version 3, these tunables are no longer
present. The system will establish an initial size for the ta‐
ble, 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 ker‐
nel's dynamic address space.
This array has historically been statically-sized. That means certain
pathological workloads that fragment 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:
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 par‐
ticular workload. When the default value is overridden, the kernel may
increase the value beyond the your specification depending on the sys‐
tem size.
There are different tunables for 32- and 64-bit kernel because the
64-bit kernel has more virtual address space. The tunable controls
32-bit kernels and the tunable controls 64-bit kernels.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parame‐
ter 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 val‐
ues. For information about the effects of installation on tunable val‐
ues, consult the documentation for the kernel software being installed.
For information about optional kernel software that was factory
installed on your system, see at
AUTHOR
and were developed by HP.
OBSOLETED Tunable Kernel Parameters nsysmap(5)
