[Beowulf] Core 2 Duo Bugs: Any importance in the beowulf field?

Vincent Diepeveen diep at xs4all.nl
Mon Nov 13 16:13:37 PST 2006


good all mighty 

"AI39. Cache Data Access Request from One Core Hitting a Modified Line in
the L1 Data Cache of the Other Core May Cause Unpredictable System
Behavior
When request for data from Core 1 results in a L1 cache miss, the request is
Problem:
sent to the L2 cache. If this request hits a modified line in the L1 data cache
of Core 2, certain internal conditions may cause incorrect data to be returned
to the Core 1."

with such a hardware bug you just can't garantuee parallel correctness.
my entire parallellism is based upon this.

hope they fix that chip and ship around new ones to customers. 
no bios is gonna fix such a cache bug of course.
  ----- Original Message ----- 
  From: Jones de Andrade 
  Cc: beowulf at beowulf.org 
  Sent: Monday, November 13, 2006 11:37 PM
  Subject: Re: [Beowulf] Core 2 Duo Bugs: Any importance in the beowulf field?


  Hi!

  Thanks a lot for the answer.

  Anyway, I would like to go a bit deeper on this subject. I know that there are this kind of problems in every processor. I know that the number 39 is the one of real concer. But we also know that still it seems to NOT have a fix, work around ou bios update for it. So I would like to know if this is of real concern in the field of clustering and beowulfs, and what are the impressions people are having on these processors (and what kind of "way-around" is being used). 

  Thanks a lot in advance for everything,

  Sincerally yours,

  Jones


  On 11/11/06, Douglas Eadline < deadline at clustermonkey.net> wrote:

    Generally these issues are handled by compilers, BIOS, microcode 
    updates, and steppings of the processor. All new processors have
    a list of bugs. The AI 39 seems to be of some concern.

    Check this document,

    http://www.intel.com/design/processor/specupdt/313279.htm

    Again, don't be alarmed this is standard for all processors.

    --
    Doug



    > Hi all.
    >
    > Wel, let me go straigh to the point: I'm a begginer, more or less 
    > enthusiastic about the beowulf world. I've been keeping track of this list
    > for a good time.
    >
    > I would like to aks just one single (and probably stupid) question: A few
    > months ago, Intel released a small list of bugs of the first version of 
    > the
    > Core 2 chips family. Much discussion has gone around the web about whether
    > or not these bugs (or some, or any of them) would affect any class of
    > users.
    >
    > I haven't seen such a discussion here. I would like to know if there 
    > aren't
    > any concerns on using this chips in the kind ofapplication beowulfs are
    > usually used? Specially for scientific applications?
    >
    > And what's the experience anyone got with those chips? Good, bad... 
    >
    > Thanks a lot in advance, and sorry for wasting your tie,
    >
    > Sincerally yours,
    >
    > Jones
    > _______________________________________________
    > Beowulf mailing list, Beowulf at beowulf.org
    > To change your subscription (digest mode or unsubscribe) visit
    > http://www.beowulf.org/mailman/listinfo/beowulf
    >


    --
    Doug





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