Just reading the description and not having peeked into the sniffer trace, I wondered if is it this behavior a side effect of mitigation of [1], consequently, are the linux side sockets marked as no_delay ? [2]
[1]: https://en.wikipedia.org/wiki/Silly_window_syndrome [2]: https://stackoverflow.com/questions/17842406/how-would-one-disable-nagles-algorithm-in-linux --a On 7/24/19, Florin Coras <fcoras.li...@gmail.com> wrote: > Hi, > > It seems that linux is reluctant to send a segment smaller than the mss, so > it probably delays sending it. Since there’s little fifo space, that’s > pretty much unavoidable. > > Still, note that as you increase the number of sessions, if all send traffic > at the same rate, then their fair share will be considerably lower than the > maximum you can achieve on your interfaces. If you expect some sessions to > be “elephant flows”, you could solve the issue by growing their fifos (see > segment_manager_grow_fifo) from the app. The builtin tcp proxy does not > support this at this time, so you’ll have to do it yourself. > > Florin > >> On Jul 24, 2019, at 1:34 AM, max1976 via Lists.Fd.Io >> <max1976=mail...@lists.fd.io> wrote: >> >> Hello, >> >> Experimenting with the size of fifo, I saw a problem. The smaller the size >> of the fifo, the more often tcp window overflow errors occur (Segment not >> in receive window in vpp terminology). In the dump [1], is shown the data >> exchange between the vpp tcp proxy (192.168.0.1) and the nginx server >> under Linux (192.168.0.200), the size of the rx fifo in the vpp is set to >> 8192 bytes. The red arrow indicates that the vpp is waiting for the latest >> data to fill the buffer. The green arrow indicates that the Linux host >> stack is sending data with a significant delay. >> This behavior significantly reduces throughput. I plan to use a large >> number of simultaneous sessions, so I can not set the size of the fifo too >> large. How can I solve this problem? >> >> Thanks. >> [1] https://monosnap.com/file/XfDjcqvpofIR7fJ6lEXgoyCB17LdfY >> -=-=-=-=-=-=-=-=-=-=-=- >> Links: You receive all messages sent to this group. >> >> View/Reply Online (#13555): https://lists.fd.io/g/vpp-dev/message/13555 >> Mute This Topic: https://lists.fd.io/mt/32582078/675152 >> Group Owner: vpp-dev+ow...@lists.fd.io >> Unsubscribe: https://lists.fd.io/g/vpp-dev/unsub >> [fcoras.li...@gmail.com] >> -=-=-=-=-=-=-=-=-=-=-=- > >
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