RE: [Info-ingres] ii_num_processors/ii_max_sem_loops

> What can you tell me about these parameters for Ingres on OpenVMS
> (Ingres 2.0/Alpha VMS 7.3-1). Are these parameters that must be set
> for VMS? I haven't heard of these before, and vaguely remember not to
> use them in the VMS environment. Can you help me here?

They can be used in a VMS environment as far as I know. A quick summary:

II_NUM_OF_PROCESSORS - affects the logic behind MUTEX acquisition. If
set to 1 a thread will go to sleep if it is waiting for MUTEX it cannot
get. The reasoning is thread that has the mutex needs to complete its
work so before any other thread can use it. With a value of 2 or more a
waiting thread will spin for a number of times before going to sleep.
This assumes the thread with the needed mutex is running on another
process.

II_MAX_SEM_LOOPS - defines the number times a thread will spin/loop
before going to sleep. Default is 2000 if not defined.

> I am working off an OpenVMS 7.3-1 HP Alpha system with Ingres 2.0. My
> Alpha has 4 processors and 5 Gb Memory. We have 4 DBMS servers, 4 GCC
> servers.

I have seen it used on a 4 quad GS160 with 16GB memory and between 8 and
10 DBMS servers. IIRC it was with OpenVMS 7.1-H2 and Ingres 2.0 with
both AXP and AXM flavours.

It is probably only useful if you see excessive MUTEX waits within
iimonitor.


> Thanks,
>
> K Brien
>