Reducing system memory utilization

[Dan Copeland]

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

[Chris Wilshaw]

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.

[Pete Randall]

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

[Mark Greene_1]

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

[Dan Copeland]

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

[Dan Copeland]

2nd try on the attachment...

[Patrick Wallek]

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

[Pete Randall]

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

[Sridhar Bhaskarla]

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