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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