Re: [myrinet] Re: Re: Fast Directed Writes

On Wed, Sep 05, 2001 at 03:32:35PM -0400, Umit Rencuzogullari wrote:

> Thanks for the information. In my previous mail, I tried to simplify
> things for easy understanding. Actually we need to set two flags as
> follows.

Ah. So the fundamental tradeoff is:

1) Poll 1 global flag on the receiver, and every send
   requires a separate send just to set that flag, or
2) Poll N per processor flags on the receiver.

> If there is a way of setting this 1 word long flag with a
> register write, this will save us a great hassle.

The way to do it is with a normal directed send, which takes around 9
useconds on today's Lanai. The DMA doesn't make it slow.

g