Why is NFSv4 so slow?

[Rick Macklem]

On Mon, 28 Jun 2010, Rick C. Petty wrote:

> On Mon, Jun 28, 2010 at 12:35:14AM -0400, Rick Macklem wrote:
>>
>> Being stuck in "newnfsreq" means that it is trying to establish a TCP
>> connection with the server (again smells like some networking issue).
>> <snip>
>> Disabling delegations is the next step. (They aren't
>> required for correct behaviour and are disabled by default because
>> they are the "greenest" part of the implementation.)
>
> After disabling delegations, I was able to build world and kernel on two
> different clients, and my port build problems went away as well.
>
I was able to reproduce a problem when delegations are enabled and the
"rdirplus" option was used on a mount. Since I haven't done non-trivial
testing with "rdirplus" set, but have done quite a bit with delegations
enabled for mounts without "rdirplus", I suspect the problem is related
to using "rdirplus" on NFSv4 mounts.

So, I'd recommend against using "rdirplus" on NFSv4 mounts until the
problem gets resolved.

You could try re-enabling delegations and the try mounts without 
"rdirplus" and see if the problems during builds still show up?

Thanks for your help with testing, rick