aio_proc_max.5 (2010 09)

aio_proc_max(5) aio_proc_max(5)

(Tunable Kernel Parameters)

further is that more system resources can be used for asynchronous I/Os.

When Should the Value of This Tunable Be Lowered?

aio_proc_max should be lowered when AIO performance is acceptable but there is concern about too

many system resources being devoted to AIO.

What Are the Side Effects of Lowering the Value of This Tunable?

As long as it remains a positive value, lowering the value of this tunable simply decreases the number of

I/Os that each process can issue. When this tunable is set to 0, it will cease to have an effect, and the sys-

tem will enforce only the old system-wide tunables described above (see DESCRIPTION).

What Other Tunables Should Be Changed at the Same Time as This One?

No additional tunables need to be changed at the same time as this one.

However,

aio_iosize_max

can optionally be set if there is an interest in limiting memory usage for

AIO.

In addition, when

aio_proc_max is set to a positive value, another option is to lower the values of the

older system wide limits (such as aio_max_ops

and aio_physmem_pct).

This is useful because the

older limits will have no impact on aio_reap (2) users, and aio_reap (2) users are expected to consume the

majority of system resources. (Leaving less resources for processes governed by the older limits)

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

aio_proc_max was developed by HP.