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Re: Firefly & Q9660 CPU

Alex Granovsky
gran@classic.chem.msu.su


Hi,

we are aware of this problem. In brief, some of recent Intel's
processors do not follow Intel's own latest specification on the
CPUID instruction. More precise, these processors claim they
support CPUID function 0xb, but fail to provide any meaningful
result.

You can file bug report to Intel asking for microcode update,
then ask your motherboard/BIOS manufacturers to release updated
BIOS.

The simpler workaround is to use the following additional
command line arguments to launch Firefly and force it to
override invalid results returned by CPUID:


pcgamess.exe ...some arguments... -ncores 2 -nthreads 1

on dual-core processors having this bug, and:


pcgamess.exe ...some arguments... -ncores 4 -nthreads 1

on quad-core CPUs.

Here, the argument of ncores switch is the number of physical
CPU cores per each CPU.

Similarly, the argument of nthreads switch is the number of
logical cores cores per each single CPU core. It should be
set to 1, unless you are using HTT-enabled processors, however,
the latter do not have this nasty bug and thus you do not need to
use these additional arguments at all.

The workaround for this problem has been already developed,
and we plan to update binaries on our server within a week
or so.

-Alex

On Mon Feb 2 '09 10:58am, Andrey Safonov wrote
----------------------------------------------
>Hello, Firefly world!

>I have encountered such a problem: Firefly succefully runs on my older machines with Core2 Quad Q6600 CPU and fails on my newer machine with Q9550. The outputs are the following.

>Q6600:
> Intel Core2/ Win32  PC GAMESS version running under Windows NT
> Running on Intel CPU:  Brand ID  0, Family  6, Model  15, Stepping 11
> CPU Brand String    :  Intel(R) Core(TM)2 Quad CPU    Q6600  @ 2.40GHz
> CPU Features        :  CMOV, MMX, SSE, SSE2, SSE3, SSSE3, MWAIT, EM64T
> Data cache size     :  L1 32 KB, L2 4096 KB, L3     0 KB
> CPU frequency is    :  2405.510 MHz
> max    # of   cores/package :   4
> max    # of threads/package :   4
> max     cache sharing level :   2
> Operating System successfully passed SSE support test.
> PARALLEL VERSION (UNIFIED) RUNNING SEQUENTIALLY ON SINGLE NODE
>.............

> Q9550:
> Intel Core2/ Win32  PC GAMESS version running under Windows NT
> Running on Intel CPU:  Brand ID  0, Family  6, Model  23, Stepping 10
> CPU Brand String    :  Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz
> CPU Features        :  CMOV, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, MWAIT, EM64T
> Data cache size     :  L1 32 KB, L2 6144 KB, L3     0 KB
> CPU frequency is    :  2833.000 MHz
> max    # of   cores/package :   4
> max    # of threads/package :   4
> max     cache sharing level :   2
>*ERR* KO-04 integer divide by zero

>Does anybody know, the reason is in Firefly, Q9550, or my bent hands?


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