Subject: Re: [ (Cron Daemon): cron for cgd@sun-lamp said this]
To: None <cgd@nobozo.CS.Berkeley.EDU,>
From: Mike Hibler <>
List: tech-kern
Date: 11/05/1993 18:45:23
> i've begun collecting memory stats for lamp again...
> what do the CouldFree Numbers mean?
> what can we do about them?

I believe "couldfree" reflects times when kernel malloc could have given
memory back to the system from a bucket.  Specifically, when a free is
done that "completes" a page (i.e. one page is broken into N elements
and now all N elements are free) and the amount of memory in that bucket
is over the high water mark (arbitrarily set at this point).

The "free" is not actually done right now.  Note that this is not
necessarily the right thing to do as your bucket could be hovering right
around a page boundary such that every new request allocates a page and
and every free deallocates that page.  It depends on the nature of the
allocations from that bucket.

This feature can be useful if the average memory use is well below the
peak use (i.e. there are spikes in the memory usage).