[luau] memory and writes to disk - linux behavior question

[Charles Lockhart]

I have a "dedicated system" (what do you call a system that's obviously 
not embedded but is designed (destined?) for a very narrow scope of 
operation?), a Compaq DL360 G1 box whose sole purpose in this existence 
is to run an application we have.

The system's got 512 MB main memory.  When we first power up, according 
to top, pretty much all of that is free.  When we start the application, 
it takes up some, but still there's a lot of memory free.

Then the application starts doing disk writes.  It's streaming imaging 
data to disk at sustained rates as high as 30MBPS.  I'm running top to 
get an idea of what's going on, and I watch the free memory sink to 
about 3MB of data free.  It seems like the application hogs all the 
memory resources available.  This is fine with me, I don't really want 
anything else running that isn't somehow supporting this application, 
but it looks kind of funky and I wonder what's going on.

Any ideas as to what may be going on?  Is top lying, am I 
misinterpreting the value that top is showing, is all the memory getting 
mapped to the process even though it may not be completely used?

-Charles


-- 
Charles Lockhart
Embedded Software Engineer
NASA InfraRed Telescope Facility
http://irtf.ifa.hawaii.edu/~lockhart
lockhart at irtf.ifa.hawaii.edu
(808)956-7635