----- Original Message -----
From: "Sven Willenberger" <[EMAIL PROTECTED]>
To: "Jeremy Chadwick" <[EMAIL PROTECTED]>
Cc: <freebsd-stable@FreeBSD.org>
Sent: Friday, April 20, 2007 6:25 PM
Subject: Re: CARP and em0 timeout watchdog
On Fri, 2007-04-20 at 09:04 -0700, Jeremy Chadwick wrote:
On Fri, Apr 20, 2007 at 11:51:56AM -0400, Sven Willenberger wrote:
> Having done more diagnostics I have found out it is not CARP related at
> all. It turns out that the same timeouts will happen when ftp'ing to
> the
> physical address IPs as well. There is also an odd situation here
> depending on which protocol I use. The two boxes are connected to a
> Dell
> Powerconnect 2616 gig switch with CAT6. If I scp files from the
> 192.168.0.18 to the 192.168.0.19 box I can transfer gigs worth without
> a
> hiccup (I used dd to create various sized testfiles from 32M to 1G in
> size and just scp testfile* to the other box). On the other hand, if I
> connect to 192.168.0.19 using ftp (either active or passive) where ftp
> is being run through inetd, the interface resets (watchdog) within
> seconds (a few MBs) of traffic. Enabling polling does nothing, nor does
> changing net.inet.tcp.{recv,send}space. Any ideas why I would be seeing
> such behavioral differences between scp and ftp?
You'll get a much higher throughput rate with FTP than you will with
SSH, simply because encryption overhead is quite high (even with the
Blowfish cipher). With a very fast processor and on a gigE network
you'll probably see 8-9MByte/sec via SSH while 60-70MByte/sec via FTP.
That's the only difference I can think of.
The watchdog resets I can't explain; Jack Vogel should be able to assist
with that. But it sounds like the resets only happen under very high
throughput conditions (which is why you'd see it with FTP but not SSH).
I guess it is possible that the traffic from ftp (or smb) is overloading
the interface; fwiw, if I increase the {recv,send}space to 131072 I can
acheive 32MB+/s using scp (and ftp shows similar values). The real
question is how to avoid these watchdog timeouts during heavy traffic;
the whole point here was to replace windows-based fileshare servers with
FreeBSD for the local network but at the moment it is proving
ineffectual as any samba file transfers stall (much like ftp). I see no
other error messages in the logfiles other than the watchdog timeouts
plus interface down/up messages.
Sven
Sorry for jumping on a thread here. I've had issues with em NIC's as well.
Especially with heavy loads. What helped for me was turning on polling. I
recompiled the kernel with polling and turned it on in rc.conf and my
problems disappeared.
Are you running with polling on?
-Clay
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