Date: Thu, 26 Oct 2017 10:31:22 -0400 From: Joe Buehler <aspam@cox.net> To: Vincenzo Maffione <v.maffione@gmail.com> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: virtio_net / netmap RX dropping frames Message-ID: <59F1F1BA.3020608@cox.net> In-Reply-To: <S7hQ1w00l19hflM017hQgB> References: <59F0FBEE.6030008@cox.net> <S7hQ1w00l19hflM017hQgB>
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Vincenzo Maffione wrote: > I guess you are using a FreeBSD guest. Is this the case? If you have the Sorry, I am using LINUX, ubuntu 16.04 LTS for both host and VM. I am posting here at standing request of netmap driver author. The host has 24 CPUs @ 2.5 GHz and 128G of memory and is *idle* so I am a bit disappointed > chance, try a linux guest to check if virtio-net works better there > (I've used netmap on the netmap-patched virtio-net in Linux guests, > never tried on FreeBSD). > The netmap ring size is just the NIC ring size. If you change the > virtio-net NIC ring size (sysctl on FreeBSD, I guess). OK I'll look into that. I increased the ring size on the host ixgbe but that had no effect so I guess it must be virtio_net. > Anyway, for your specific use-case (VM accessing the physical 10G NIC) > there is a way better solution, which is the netmap passthrough. Unfortunately I don't have control of the host, just the VM, so pt netmap is not an option. My initial query regarded frame drops but the latency is also pretty bad. The LINUX ping utility inside the VM says 0.2 mS consistently without netmap in use. My app sees that value for almost all frames but it spikes (up to 0.6 mS!) for a few frames, which is not acceptable for this application -- was expecting much better due to network stack bypass. And this is just 100 frames/sec... Joe Buehler
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