Re: Milestones document

[jg pa dec com (Jim Gettys)]

First thing to do is identify performance problems.  Better system
level profiling tools are coming to Linux Real Soon Now, and as soon
as they are, we should use them.  I'm poking at things here; as soon
as I can say things more publically, I will.

Certainly I/O is slowest: using memory of course can force paging,
and when you are, you lose; but using memory for caches of information
can also be a win (so long as you aren't paging).

There is generally some low hanging fruit, as well as more serious work:

For example, the next time you break library binary compatibility, you 
go through all data structures and sort the structure elements small to 
large, (often with subunits of information that ought to be local in a 
cache line), as well as recalculation kinds of things.  As I remember, 
in the X server case, memory usage, outside of backing store, dropped 
by maybe 30% by this simple dicipline, while increasing performance.
somewhat.

So some of this simple stuff is where to start, and then it will be time
to understand where to put serious work, once we have the tools to tell
us where to expend effort.
				- Jim

--
Jim Gettys
Technology and Corporate Development
Compaq Computer Corporation
jg@pa.dec.com