Re: PX Deq Credit: send blkd

Martin
 As you correctly pointed out, PX slaved are blocked.
One obvious reason I can think is smaller large pool. What is your large pool size set to ? Do you use ASMM - Automatic Shared memory management stuff? If yes, do you see any growth or shrink for large pool ? If large pool is not configured, it is possible that shared pool fragmentation to cause PX slaves to wait for these PX events. v$sgastat is a good place to start. What other events do you in statspack report or AWR report during that time frame? 

Cheers
Riyaj Shamsudeen
The Pythian Group
Personal : http://orainternals.wordpress.com

Martin Klier wrote:

Hi list,

I've got massive wait events named "PX Deq Credit: send blkd". As far as
I know, that's a parallel query issue, a producer is faster then the
consumer. But thats a textbook explanantion I simply don't understand.
The obvious option, to increase PARALLEL_EXECUTION_MESSAGE_SIZE, does
not fit since it's set to the (x86_64) architecture's maximum, 64k.

The system is rather capable, and CPU load is less than 30%, disk IO
around 100MB/s, the underlying ASM diskgroups have been successfully
tested with nearly 1GB/s.

The query in question is a huge MERGE statement with APPEND PARALLEL
hints, a little abstracted form here:


....
--
http://www.freelists.org/webpage/oracle-l

Other related posts: