kern/131360: [nfs] poor scaling behavior of the NFS server
martin at email.aon.at
Sat Feb 7 07:40:06 PST 2009
The following reply was made to PR kern/131360; it has been noted by GNATS.
From: Martin Birgmeier <martin at email.aon.at>
To: bug-followup at FreeBSD.org
Subject: Re: kern/131360: [nfs] poor scaling behavior of the NFS server under load
Date: Sat, 7 Feb 2009 16:31:21 +0100 (CET)
I am now very sure that this is an interaction with pppoa, and it is
also worse than I originally thought: it will even lead to failed NFS
transactions for the client.
Here is what I have:
Machine A ('server', a mini home server) does the following:
- connecting to the Internet using usermode ppp over pppoa over an
Alcatel ADSL modem
- NFS serving FreeBSD sources
Machine B does the following:
- Mounting the FreeBSD sources from A (using amd), under directory
- Compiling the FreeBSD sources: make -j4 buildworld, such that the
corresponding obj is local (via amd again)
Especially in the first phase of the buildworld (clean, depend, obj),
there is a lot of simultaneous NFS traffic from B to A. As soon as
a download is started at A (going via pppoa, of course), the load on
A rises to very high values (> 20 not uncommon).
This may lead to B aborting the compile, it just did that with
"directory not found".
Both machines are running 7.1.0.
No such problem happended when both were running 6.3.0.
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