[SCore-users] Score 4.2.1 on new Athlon systems.

[Nick Birkett]

On Thursday 07 March 2002 05:49, you wrote:
> Hi.
>
> From: Nick Birkett <nrcb at streamline-computing.com>
> Subject: [SCore-users] Score 4.2.1 on new Athlon systems.
> Date: Thu, 7 Mar 2002 01:16:58 +0000
> Message-ID: <0203070116580I.19905 at pecan.comlab.ox.ac.uk>
> nrcb> Hi , we have been running both Score and Myricom GM.
> nrcb>
> nrcb>  We now have some new systems based on Tyan Tiger MPX multi-processor
> boards nrcb> (1.6 GHz Athlon with DDR memory).
> nrcb>
> nrcb> Pallas benchmark PMB-MPI1 compiled using -O4 -fomit-frame-pointer
> nrcb> -funroll-all-loops  and with -DnoCHECK gives very poor bandwidth
> result for nrcb> Score Myrinet2k, whereas GM gives good one.
> nrcb>
> nrcb> Score 4.2.1 gives 90Mbytes/sec point to point over Myrinet2k.
> nrcb>
> nrcb> GM/MPICH (GM 1.5, MPICH 1.2..8 and 1.2.7.. ) gives twice this
> bandwidth nrcb> over Myrinet.
> nrcb>
> nrcb> GM is using kernel 2.4.18 and  Score uses 2.4.10smp (the one that
> comes with nrcb> Score 4.2.1 binary release).
> nrcb>
> nrcb> We have compared GM and Score on other Athlon systems and do not have
> this nrcb> big difference (usually bandwidth is same within a few %).
>
> MPICH/GM uses zero-copy at default, but MPICH/SCore does not use
> zero-copy at default.
>
> Could you test the program using mpi_zerocopy=on?
>
>

Ok many thanks. We got our Myrinet cards back from another benchmark (at 
last). Sorry for the delay.

Pallas benchmark with mpi_zerocopy=on option now gives 231Mbytes/s
on Athlon MPX systems (using scrun -nodes=2x1 ), which is *EXCELLENT*.

Can Shinji or someone explain why mpi_zerocopy is off be default, but in 
MPICH-GM it is on ?
What are the advantages/disadvantages ?

Thanks,

Nick