Hi Florin, I made a simple epoll tcp proxy (using vcl) and saw the same behavior.
I increased the fifo size to 16k, but I got exactly the same effect. A full dump for a session with a buffer size of 16k can be obtained by reference [1] (192.168.0.1 is the interface on vpp, 192.168.0.200 is the linux host with nginx) . Maybe we should not allow full buffer filling? P.S. I tested several host stacks working with dpdk, but only in vpp this behavior is observed. Thanks. [1] https://drive.google.com/open?id=1JV1zSpggwEoWdeddDR8lcY3yeQRY6-B3 >Среда, 24 июля 2019, 17:45 +03:00 от Florin Coras <fcoras.li...@gmail.com>: > >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] >> -=-=-=-=-=-=-=-=-=-=-=- > >-=-=-=-=-=-=-=-=-=-=-=- >Links: You receive all messages sent to this group. > >View/Reply Online (#13567): https://lists.fd.io/g/vpp-dev/message/13567 >Mute This Topic: https://lists.fd.io/mt/32582078/1863201 >Group Owner: vpp-dev+ow...@lists.fd.io >Unsubscribe: https://lists.fd.io/g/vpp-dev/unsub [max1...@mail.ru] >-=-=-=-=-=-=-=-=-=-=-=- -- Max A.
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