Date: Sat, 19 Apr 2014 09:11:59 -0300 From: Tiago Ribeiro <shasty@gmail.com> To: "seanrees@gmail.com" <seanrees@gmail.com> Cc: "freebsd-xen@freebsd.org" <freebsd-xen@freebsd.org> Subject: Re: VM in Xen 4.1; poor packet forwarding performance on xn0 Message-ID: <2C3A747F-DA88-4815-A930-7C5EB1CD6238@gmail.com> In-Reply-To: <CAJGy1F0%2BG1zq9hVbifTM2Vq6HHEmCM9hnFvQ=4t-4d5x=npaCA@mail.gmail.com>
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> Em 18/04/2014, às 11:57, "seanrees@gmail.com" <seanrees@gmail.com> escreveu: > > Hi there freebsd-xen, > > I tried first on freebsd-questions@ without success, so I thought to retry > here. > > I run OpenVPN on a FreeBSD 10.0-Rp1 VM in Xen 4.1 (HVM). I am experiencing > slow network performance on xn0 that seems to have developed after I > upgraded to FreeBSD 10 (no other changes). I can only achieve about 0.5mbps > through this interface when forwarding packets; packets in a single > direction are fine (e.g; downloading to the VPS or pushing from the VPS) > and clock in at many (>10 usually) mbps. > > Interestingly, my identical VM (configuration managed centrally) running on > Xen 3.4 (HVM) does *not* have this issue. > > I did a little debugging and here's what I've noticed: > - Not related to OpenVPN, repro'd using ssh -d. > - Slow VM has a very low rate of context switches (~250) while > forwarding, fast VM has a lot more (~2000) sampled over 5 seconds using > systat -v. > - I can't repro a context switch limit (tried a limited fork() bomb). > - Tried with *and* without LRO and TSO on xn0 (and all combinations of > LRO and TSO on/off) > > I started digging into the Xen drivers but I realised I am not equipped to > debug this. I'm looking for suggestions on what to check. My provider is > offering to move me to an older Xen host but I'd like to see if I can help > identify a bug either in my configuration or perhaps in FreeBSD's Xen code. > > Sean > _____________________________________________ Do you use pf?home | help
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