linux performance with IA 64

[v.s.varadharajan]

Hi
I have a rx2600 Server with Linux AS 3. I am running Tomcat and Oracle on the same machine. I have 1 GB of mem on the server. The system monitor shows 100% utilisation of Memory and CPU. When same of kind of software run on normal P4 mac with 1 GB of mem is is performing better. Are there any parameters to be comfigured extra. Also we are gettting a problem saying Floating-point-error. can somebody help.

[Steven E. Protter]

100% memory utilization does not really mean much. Your system is going to allocate its memory and use it for something, even cache.

Comparison to a PC is not really relavent either, because the achitechture and what the P4 mac is doing is totally different.

I have the following recommendations.

1) See if the machine is swapping, if so, think about adding memoryh.

2) Figure out what is running resident and what kind of resources its using.

3) Itanimum is a 64 bit chip, with a corresponding large address space. Loading the will take a bit more resouces than you expect, leaving less memory for other tasks.

4) Your memory figure for oracle is way too low. They recommend a minimum of 2 GB for the database server. If you are running the app server, most shops won't try this without 4 GB of Ram.

I've got a couple of years experience running Oracle as a sysadmin backup dba on HP-UX and Linux.

SEP

[Ivan Ferreira]

There are some parameters that must be set in the java execution environment, i think its the -X parameter.

http://www.caucho.com/resin-3.0/performance/jvm-tuning.xtp

Use ipcs -a to view the memory allocated to shared memory, 1 GB is too low memory.

http://support.adobe.com/devsup/devsup.nsf/docs/52634.htm

Check if you have paging with vmstat, also get database statistics to see if you are I/O bound.

[rick jones]

In addition to the excellent suggestions already made:

Please cut and pate the actual "floating point error" message.

IIRC the AS3 bits are a 2.4 kernel. In broad handwaving terms, 2.6 kernels are better for IA64. On 2.6 kernels you can use things like Caliper (http://www.hp.com/go/caliper) or q-syscollect (somewhere off of www.hpl.hp.com) to get an idea of where CPU is being consumed. It would be useful to know user versus system, which routines were "big" and the like.

Might check the netstat -s statistics if there is much networking going-on.

[Rick Beldin]

When you talk about Linux, you really, really, really need to show the kernel revision you are using. uname -a will give you everything that is necessary.

If you are using RHEL3 U3, you need to upgrade. That particular kernel revision (2.4.21-20) had a problem where under memory pressure, kswapd would consume cpu cycles and because it was a kernel thread, was unkillable. U3 had other memory-related problems that caused it to be a fairly unstable os.

U4 was better in this regard, but had some problems with memory corruption (bad). U5 seems to be pretty stable.