Date: Sun, 13 Jul 2003 17:24:14 -0700
From: "David S. Miller" <davem@redhat.com>
To: Larry McVoy <lm@bitmover.com>
Cc: lm@bitmover.com, roland@topspin.com, alan@storlinksemi.com,
       linux-kernel@vger.kernel.org, linux-net@vger.kernel.org,
       netdev@oss.sgi.com
Subject: Re: TCP IP Offloading Interface
Message-Id: <20030713172414.5c888094.davem@redhat.com>
In-Reply-To: <20030714002200.GA24697@work.bitmover.com>
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On Sun, 13 Jul 2003 17:22:00 -0700
Larry McVoy <lm@bitmover.com> 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.
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