Re: TCP IP Offloading Interface

On Sun, 13 Jul 2003 17:22:00 -0700
Larry McVoy [off-list ref] wrote:

Hey, maybe it isn't, but could you please quantify the cost of the VM 
operations?  How hard is that?

Ok.

So the page is in a non-uptodate state, NFS would have it locked,
and anyone else trying to get at it would sleep.

This page we have currently is "dummy" in that it is only a place
holder in case we don't get a full page from the networking.

We have all the infrastructure to do everything up to this point.

Next, if the networking gave us a full page, we'd "replace"
the dummy page with this one, which would involve:

1) delete the dummy page from the lookup, insert the networking's
   page

2) arrange so that all sleepers on the dummy page will do a relookup
   and find the new page

And when we're done with the operation we wake everyone up.

I can't see any part of this turning out to be expensive.