Date: Wed, 06 Mar 2013 14:40:38 -0800 From: Colin Percival <cperciva@freebsd.org> To: Jay West <jwest@ezwind.net> Cc: freebsd-xen@freebsd.org Subject: Re: misc. questions Message-ID: <5137C5E6.2070802@freebsd.org> In-Reply-To: <000901ce1aa7$90704320$b150c960$@ezwind.net> References: <000901ce1aa7$90704320$b150c960$@ezwind.net>
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On 03/06/13 12:17, Jay West wrote: > 1) One or two of our freebsd 9.1 HVM (with PVM drivers) under > Xenserver 6.1 advanced are fairly frequently generating this message on the > console: xn_txeof: WARNING: response is -1! Any ideas what this may be and > what should be done? It does seem to only occur on the machines that have > higher network load than the others. I see this on EC2 (running under HVM) as well. It doesn't seem to interfere with anything and only occurs occasionally (maybe five times per GB of network traffic?) so I haven't worried too much about it -- but if anyone has a clue about this I'd love to fix it from the "tidy up loose ends" perspective. > 2) We did a pilot project of about 8 VM's (the above mentioned > environment) and all went well. Now that we've moved it into production with > many more VM's, I'm wondering about recommended tuning. I seem to recall > from watching this list that there are a few sysctl's and the like that are > highly recommended, I think they had to do with network settings and turning > off "offloading" or somesuch. Does anyone have a quick & dirty list of > "here's the first things you should always change" with regards to FreeBSD > HVM (pvm drivers) under XenServer? You'll want to turn off tso, since it produces long mbuf chains which most xn netbacks choke on. (I have a very ugly workaround patch for this which I use on EC2, but simply turning off tso is enough unless you need Gbps+ speeds). There's a separate issue affecting pf+tso+xn (possibly pf+tso generally) which I haven't gotten around to tracking down. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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