Re: utility for testing ram?

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Fri, 2 Oct 1998 11:04:34 +0200 (MEST)

Doug Ledford wrote:
> Stephen C. Tweedie wrote:
> >
> > Hi,
> >
> > On Mon, 28 Sep 1998 23:30:18 -0500, Doug Ledford <dledford@dialnet.net>
> > said:
> >
> > >> Start it running overnight, if it's still running when you wake up, your
> > >> memory's likely to be ok.
> >
> > > No, no, and NO! If you want to test your RAM, you can't run some test that
> > > is CPU power limited. You'll never access your RAM here faster than the CPU
> > > can compile the kernel
> >
> > Actually, gcc has such a large working set that it turns out to be a
> > very good test indeed at least for cache memory. On a 166MHz alpha UDB,
> > anything which fits into L1 cache absolutely flies, but kernel compiles
> > take about 4 times as long as on my 486-DX100 simply due the the UDB's
> > crippled L2 cache size and off-CPU memory bandwidth. Unless you have a
> > massive L1 cache like the new 21264s have, gcc speed is quite likely to
> > be influenced as much by L2 memory performance as by raw CPU speed.
>
> I'll stand by my claim that my test will trounce a gcc compile test any day
> of the week for finding bad RAM %^) The compile test may touch a lot of
> RAM, may have a large working set, and may actually compute things fairly
> quickly, but gcc can't compile, k for k, as fast as gzip can decompress the
> kernel. Then add in the significantly larger amount of data you are running
> through RAM in a short period of time via DMA from the disk sub-system and
> the compile test won't be able to match the stress the test I listed gives
> your machine. I can say this much from experience. Find a machine that
> fails my test on one out of every four passes, and I'll show you a machine
> that will compile kernels all day long without a hiccup (x86 arch anyway).

What is "my test" again? A memory test? Could I possibly have your test?

I have all memory tests from the memory testing book from A.J. van de
Goor in "chipmunk" and they find very little problems with PCs that
gcc crashes on...

Roger.

-- 
| Most people would die sooner than think....  |    R.E.Wolff@BitWizard.nl 
| in fact, most do.  -- Bertrand Russsell      |     phone: +31-15-2137555 
We write Linux device drivers for any device you may have! fax: ..-2138217


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