topic Re: Memory/Buffer memory clear in OpenVMS in Operating System - OpenVMS

Memory/Buffer memory clear in OpenVMS

Sumant M Kumar — Thu, 03 Apr 2014 05:39:33 GMT

Dear Experts,

Is there any command in OpenVMS to clear memory/buffer memory for better system performance. We can do memory clear in RHEL but how we can do in OpenVMS? Please suggest

Regards,

SK Mishra

Re: Memory/Buffer memory clear in OpenVMS

Steven Schweda — Thu, 03 Apr 2014 18:12:41 GMT

Re: Memory/Buffer memory clear in OpenVMS

Hein van den Heuvel — Thu, 03 Apr 2014 19:19:30 GMT

I recommend putting more air in the tires as a first step.

SET CACHE/RESET on it's own only clears the counters. Nothing else.

Check out: mcr sysgen HELP SYS_PARAM VCC_MAX_CACHE

Anyway.. what makes you think you can make the system better by flushing a cache?

Just because your Linux implementation is apparently broken, does not mean OpenVMS woudl be suffering form the same ailement does it?

What are the reasons you think there may or might not be a problem in this space?

Are there any problem indicators at all? Resource usage? CPU/IO/Memory? Pagefaulting?

Finally... when I think I need to decrease my system performance and want to make the cache do a worse job, then I just allocate a humongous RAM drive to steal the pages.

$ MCR SYSMAN IO CONNECT MDA0:/DRIVER=SYS$MDDRIVER/NOADAPTER

$ INIT MDA0:/size=12345678 RAM ! (6GB)

$ INIT MDA0:/size=0 ! And give it all back

Good luck!

Hein.

Meten is Weten.

Niet weten is zweten.

Re: Memory/Buffer memory clear in OpenVMS

John Gillings — Thu, 03 Apr 2014 21:44:17 GMT

I'm curious, what performance is improved by clearing memory?

By "clearing" do you mean filling them with zeros? What is the mechanism by which system performance is improved?

Do you have a performance problem that you're trying to fix? If so, what are the symptoms?

Re: Memory/Buffer memory clear in OpenVMS

MarkOfAus — Fri, 04 Apr 2014 02:25:17 GMT

Easy... @sys$system:shutdown.

Sure, it's abrupt but it fulfils your vague question...