Re: [myrinet] Performance degradation of GM!

What does gm_debug -L show, and what chipset are you using?

With the intel i840 and intel i860 chipset, we have seem the same problem with
nodes from different vendors, and the best fix has been a BIOS upgrade.

You could try patching drivers/linux/gm/gm_arch.c ... but it seems that
turning on the flag to use the chipset may or may not be enough.

sed -e '/^#define GM_INTEL_840 0/s! 0! 1!' \
        drivers/linux/gm/gm_arch.c.orig > drivers/linux/gm/gm_arch.c


On Mon, 8 Oct 2001, geoge_zhang wrote:

> Hi:
>    It's a little too silent here, and may need some noise:-)
>    We've tested the performance of GM-1.4 on our new cluster platform
> (linux2.4.4 + Myrinet2000 + 64bit 66HMz +4dual xeon SMP). The test
> results for one-way communication performance is about the same with the
>
> results reported in Myrinet website. But for two-way communication, the
> performance degrades greatly.
>    For two-way communication between two pairs nodes in the same
> direction
> (two source processes on the same node communicate with other two
> processes
> residing on another node), each way communication achieves about 50% of
> the
> performance of one-way communication (bandwidth). Which can be explained
>
> by the physical link performance limits and each way communication
> shares 50%
> of the communication capacity of one link. But for two-way communication
>
> between two pairs nodes in reverse direction, each way achieves
> only about 80% of the performance of one-way communication. As is said
> that
> Myrinet supports full-duplex link communication, then what's the cause
> for the
> performance degradation of two-way reverse communication ?
>    Any explain would be appreciated !
>
>
> Best regards
> Geoge
>
>
>
>
>
>

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