Re: Wow! Is memory ever cheap!

H. Peter Anvin
2001-05-07T19:02:51Z

Larry McVoy wrote:
> > >
> > > On the other hand, if your apps don't have built in integrity checks then
> > > ECC is pretty much a requirement.
> >
> > Isn't this pretty much saying "if you're willing to dedicate your
> > system to running nothing but Bitkeeper, you can run it really fast?"
>
> A) Fast has nothing to do with it, ECC runs at the same speed as non-ECC;

"It" meaning BitKeeper.

> B) As I said above, "if your apps don't have built in integrity checks then
> ECC is pretty much a requirement";
> C) As I said above, we use our systems for BK development, so this choice
> makes sense for us.
>
> I think the point you are really missing is that it is not an either/or
> choice. All you really need in practice is one application which is
> both heavily used and has integrity checks. It could be BitKeeper or
> something else, all that matters is that it will detect memory problems.

This is not true in my experience. YES, it will detect bad memory
configurations, but with over 2^34 memory cells to worry about -- each of
them carrying a charge of a few dozen electrons only -- you WILL have
random failures, especially if the memory is allowed to remain stale for
extended periods of time, as is very likely in a configuration like this
(think disk cache.)

Bad memory configurations is bad. However, good memory configurations
are not necessarily perfect.

-hpa

--
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