Date: Thu, 26 Oct 2017 14:04:51 -0400 From: Joe Buehler <aspam@cox.net> To: Vincenzo Maffione <v.maffione@gmail.com> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: virtio_net / netmap RX dropping frames Message-ID: <59F223C3.5040907@cox.net> In-Reply-To: <SJSB1w02T3jnPnV01JSBh6> References: <59F0FBEE.6030008@cox.net> <59F1F1BA.3020608@cox.net> <59F214F6.9060905@cox.net> <SJSB1w02T3jnPnV01JSBh6>
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Vincenzo Maffione wrote: > You can have how many threads and processes you want. The constraint is > that there must not be two threads accessing the same ring at the same > time. In this case each pktgen is accessing different rings. Thanks that was very useful info. I had run this before and got large frame drop so assumed it was a violation of threading constraints. So now I can remove a mutex from my app, which has an RX and TX thread. Running the two pkt-gen instances, I am getting a lot of RX frame drop. Based on counters, the TX frames are making it to the external loopback device, about 1 million frames/sec, which is looping them all back, but the macvtap interface on the host that feeds into the ixgbe/vhost/virtio_net/netmap interface in the VM shows about 80-90% of them as dropped. CPU usage is low in the VM, very roughly 25% for the TX thread and 5% for the RX thread. The frame rate displayed by pkt-gen and the CPU displayed by top is bouncing around. Joe Buehler
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