HIGH MP Syn on 860 Blades/w Threading

[James Cristofero]

We are running BL860 Blades (8.3-1H1) with Threads Enabled.

I've noted that MP synch goes high when the cpu performance exceed 50 % (or when Threading hits).

otherwise, no MP Synch...

Running Oracle client 10.2.0.2.0

[Hoff]

Hyperthreading?

Or DECthreads threading?

Try hyperthreading turning it off?

Itanium hyperthreading isn't the same as it can be over on some x86 boxes; hyperthreading can be selectively enabled on OpenVMS. As implemented in recent Itanium processors, the mechanism doesn't necessarily provide a performance boost; it's a fast process schedule mechanism, and that may or may not help a particular application mix.

Itanium hyperthreading isn't multiple cores or multiple processors; there aren't enough resources available to run threads in parallel.

And as is the usual and generic recommendation when any sorts of weirdnesses arise, do load the current ECO kits if you've not already done so.

[Guy Peleg]

High is not very deterministic. What
is high? 5% 80%?

MP Synch indicates contention for spinlock,
it could be almost anything. I would look
at:

1. Alignment faults. MONITOR ALIGN would
report the current rate of alignment faults
on the system. On a BL860 I would be concerned if the rate per second exceeds 100,000 (higher than 50,000 is a warning sign).

2. Run spinlock tracing: @SYS$EXAMPLE:SPL
this will create a report highlighting spinlock usage and will provide a better understanding on what is happening on the system. Either post the report here or send it to me off line (firstname.lastname@maklee.com)

Regards,

Guy Peleg
President
Maklee Engineering
http://www.maklee.com