topic Re: Reducing system memory utilization in Operating System - HP-UX

Reducing system memory utilization

Dan Copeland — Wed, 28 Jan 2004 12:10:31 GMT

Hi,

I have an rp2470 w/ 4GB of total memory that was staged from a golden image (11.11) of a much larger server (rp8400). As a result, the kernel is sized larger than it needs to be. System memory is 980MB (not including buffer cache).

What kernel parameters affect system memory usage the most? My first thought was nproc and nfile. Any other good suggestions? Attached is my kmtune output.

tia,
Frank

Re: Reducing system memory utilization

Chris Wilshaw — Wed, 28 Jan 2004 12:15:36 GMT

In addition to nproc and nfile, you should look at ninode, maxusers, npty, nstrpty, nstrtel
(all will have a fairly small overhead)

maxdsiz, maxtsiz and maxssiz have an impact on the amount of memory that a single process can use (data segment, stack segment and text segment respectively) - a process can use any amount up to the limit imposed by these values.

Re: Reducing system memory utilization

Pete Randall — Wed, 28 Jan 2004 12:16:47 GMT

Frank,

My production server, tuned for database support and lots of users, only has a 13.8MB kernel. I don't think your efforts are going to bear much fruit. The plain and simple fact is that 980MB is going to be a tight squeeze for an 11i system. Anything under 2GB is tight!

Pete

Re: Reducing system memory utilization

Mark Greene_1 — Wed, 28 Jan 2004 12:17:33 GMT

Your messaged posted without attachement. Some of the values to look at are dbc_max_pct, dbc_min_pct, maxswapchunks, maxusers, msgmax, semmsl, shmmax, and shmseg. There may be others, and there's probably inter-dependancies with the above.

mark

Re: Reducing system memory utilization

Dan Copeland — Wed, 28 Jan 2004 12:20:06 GMT

Pete,

Thanks for the input. One question though...if your kernel is only 13.8MB how do you account for the rest of the system memory used?

Frank

Re: Reducing system memory utilization

Dan Copeland — Wed, 28 Jan 2004 12:38:05 GMT

2nd try on the attachment...

Re: Reducing system memory utilization

Patrick Wallek — Wed, 28 Jan 2004 12:45:19 GMT

The first thing I notice is that some of your msg* and sem* parameters seem high. Lowering those may reduce your system memory utilization.

Re: Reducing system memory utilization

Pete Randall — Wed, 28 Jan 2004 12:50:52 GMT

Frank,

I may have misinterpreted your question. Kernel parameters can allow processes to grow without limits and you can and should have some limits on them (the others have pointed out the areas for you to look at). On the other hand, you don't want your system to end up being single-threaded because your constraints only allow one process at a time. Coming from that viewpoint, I thought maybe you were trying to shrink the actual size of your kernel - guess not, huh?!

Pete

Re: Reducing system memory utilization

Sridhar Bhaskarla — Wed, 28 Jan 2004 12:55:45 GMT

Frank,

Size of the kernel doesn't have anything to do with how much it will consume.

During the run time, system will allocate memory dymanically and it may grow overtime. For ex., vx_ninode which is JFS inode cache.

I would be worried only if it is 100% used and there are paging outs happening.

-Sri