woods@weird.com (Greg A. Woods) writes:
> well OK....  but still the overhead in the latter option is quite
> miniscule compared to the time the process spends getting the data off a
> spinning disk in the first place :-)

the time spent on the overhead is little compared to the time spent on
the I/O, sure.  but the time spent on the overhead is time that can't
be used by other processes in the system.

there's no reason to waste the cycles.


> I suppose on a tightly coupled multi-processor system that memory
> bandwidth is more of an issue and it's not just something that slows
> down the currently running process; but in a single-CPU system I don't
> think the impact on overall system throughput will be that big...

go take a look at current systems literature, for issues around lack
of memory bandwidth.  (I can think of one paper right off-hand, the
Sites and Perl paper in OSDI in ... '97?)

memory bandwidth is a big concern in modern systems, even
single-processors.  and extra copies and wasting 2x the cache space
make the problem 2x as bad.


> I did read it (again just before I posted too).  It looks pretty simple
> and straight forward to me (even simpler than the BSD copyright!):

That's interesting; that wasn't the license that i thought was on that
code...  thanks for pointing me at that.  very much.  (see the license
on e.g. CDT and vmalloc and other things on that site.)


> So it's maybe not 100% in keeping with TNF's goals (you're not free to
> make it un-free), but it's a lot less onerous than the GPL!

uh, i don't see how you figure you're not free to make it un-free.

"Permission ... for any purpose without fee [paid to AT&T] is hereby
granted," not "Permission ... to distribute without fee for any
purpose..."

All interpretations i've seen of that wording say it means you don't
have to pay a fee to them to do all that stuff.



chris