Date: Sun, 20 Apr 2014 00:34:41 -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: <42A9E3AE-0209-4038-A5D3-2713511BA59F@gmail.com> In-Reply-To: <CAJGy1F2oQDXYzeFp3cT2ZMf=AhmL5b%2B0NHZhzaYA55XvZ4_MAA@mail.gmail.com> References: <CAJGy1F0%2BG1zq9hVbifTM2Vq6HHEmCM9hnFvQ=4t-4d5x=npaCA@mail.gmail.com> <2C3A747F-DA88-4815-A930-7C5EB1CD6238@gmail.com> <CAJGy1F2oQDXYzeFp3cT2ZMf=AhmL5b%2B0NHZhzaYA55XvZ4_MAA@mail.gmail.com>
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Em 19/04/2014, =C3=A0s 10:17, "seanrees@gmail.com" <seanrees@gmail.com> escr= eveu: > On Sat, Apr 19, 2014 at 1:11 PM, Tiago Ribeiro <shasty@gmail.com> wrote: >=20 >=20 > > Em 18/04/2014, =C3=A0s 11:57, "seanrees@gmail.com" <seanrees@gmail.com> e= screveu: > > > > Hi there freebsd-xen, > > > > I tried first on freebsd-questions@ without success, so I thought to ret= ry > > here. > > > > I run OpenVPN on a FreeBSD 10.0-Rp1 VM in Xen 4.1 (HVM). I am experienci= ng > > slow network performance on xn0 that seems to have developed after I > > upgraded to FreeBSD 10 (no other changes). I can only achieve about 0.5m= bps > > 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 t= o > > 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 he= lp > > identify a bug either in my configuration or perhaps in FreeBSD's Xen co= de. > > > > Sean > > _____________________________________________ >=20 >=20 > Do you use pf? >=20 > I do. Fairly simple ruleset: default deny, a few specific port allows, NAT= . >=20 > Sean I can't help you, i'm very interested in this topic. I have case when i use x= enserver with freebsd 10, and pf with nat, and works ok, and case with dom0 d= ebian 6 and do not work, and one case with netbsd dom0, and freebsd 9 with k= ernel compiled for xen, and works fine.=
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