topic Re: HP-UX Kernel Performance Tuning Sources in Operating System - HP-UX

HP-UX Kernel Performance Tuning Sources

Vassily Gorbounov_1 — Wed, 03 Nov 1999 05:59:39 GMT

Hi, All
I'm experiencing problems with performance on my K370 server.
Average running task queue is approx. 7-12 tasks per CPU.

Could you please advice me
1. Information sources where complete reference on fine tuning HP-UX kernel
performance could be found.

2. Parameters from different diagnostic problems (vmstat etc.) that could help
to find bottlenecks of the system.

Thanks in advance
Vassily Gorbounov
Russia

Re: HP-UX Kernel Performance Tuning Sources

Jason Luginbuhl_1 — Wed, 03 Nov 1999 08:42:24 GMT

Unfortunately, tuning Kernel Parameters is rarely effective in resolving CPU
bottleneck issues. Generally speaking, fixing CPU bottlenecks involves changing
how the system is managed rather than how the kernel is setup. For example, you
might have to schedule certain jobs for non-peak hours, optimize the
application that is "hogging" the CPU(s), nice(1) less important processes,
consider additional (purchaseable) products to control how CPU resources are
allocated, and/or add additional Processors.

The following are some good indicators of a CPU bottleneck:
-Zero percent idle CPU time (sar -u, top);
-With zero percent idle, high percent user CPU time compared to system CPU time
(sar -u, top);
-Large run queue size sustained over time (vmstat 5 30, uptime);
-Many processes blocked on priority (Glance);
-Slow response time;
-High percent system CPU time (sar -u, top)

If you are looking for information on Kernel Parameters, a good place to start
is to go into SAM's kernel parameter section and go to the "Help" section.
There is information and a description of each parameter there. As for
recommendations for specific things to tune, there is no real good central
resource that I am aware of as each system environment is different. For
specific insights on what should be tuned, a full examination of the
environment would generally be necessary and adviseable.

Re: HP-UX Kernel Performance Tuning Sources

Alan Riggs_1 — Wed, 03 Nov 1999 15:16:19 GMT

Jason is correct that most performance issues relate to things outside the
kernel, though there are some configureable kernel parameters that can have
significant performance impact. dbc_min/max_pct (or static buffering),
timeslice, and swapmem_on to name a few. Still -- it is important to collect
metrics first before undertaking any tuning effort. In particular you need to
determine where your system is getting bound: CPU, disk I/O, or network.
Glance and sar are very useful in narrowing this down, but be aware that glance
is quite CPU impactive. Look also at iostat, vmstat, swapinfo, and timex to
benchmark process times. Tuning is a complex interactive process, but there
are several excellent books on the subject available. One I have found useful
is:
HP-UX Tuning and Performance
by Robert F. Sauers and Peter S. Weygant