From: Unix-Admin (Unix-admin@triad.rr.com)
Date: Thu Aug 01 2002 - 20:12:06 EDT
List,
I got two replies. One from Rita Workman and one from Ed.
Thanks
Ed
What you see in swapinfo for memory is not the amount of physical memory but "the amount of system memory that can be used to hold pages in the event that all of the above paging areas are used up" aka pseudo-swap (see 'man swapinfo').
What you see in top for memory is the amount of free virtual memory.
Another thing is: why don't you make the priorities equal for both swap devices. Your system may be able to swap faster if you do.
To answer your other question:
pseudo-swap is always 75% of physical RAM, so 75% of 2GB is indeed 1.5GB. Nothing wrong with your system.
Rita
First, top is just a snapshot...it reflects the physical memory that is available for use at that given moment. Now swapinfo is reflective of all the space available..and remember this includes those physical disks you set up for swapping/paging. If you have pseudo_swap enabled the system will actually use more memory than is actually physically there, because it can use virtual memory and move things in and out of active memory. Gets a bit confusing.
On your swapinfo you posted you question why is your memory 2gb, but you only see 1.5gb on that...notice you have reserved a portion of memory. This is controlled by the dbc_max_pct parm. The default is 50 (way too high)...what is yours set at? And as a general rule of thumb I tend to set mine to 10 for max and 5 for min (than I tweek a little till it's just right).
Now on swapinfo, when you run this you get the total of all space available for processing use (remember you reserved xx for system) and this include physical memory and those disks you set up for swap/paging. So in total your using 82% of physical memory and overall with disk your utilization is 76% (27% of the time your hitting disk). To improve performance you need get your processing off the disk and back into memory. Take a look at your parms and see if you can adjust a couple things....or more than likely you need to add some more memory to improve performance.
There's a good doc on mem_mgt...look at /usr/share/doc for some great papers on a variety of subjects !
Thanks
Tom
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