Date: Thu, 26 Oct 2017 20:06:42 -0500 From: Xiaoye Sun <Xiaoye.Sun@rice.edu> To: FreeBSD Net <freebsd-net@freebsd.org> Subject: [netmap] when does a packet in the netmap ring send out exactly Message-ID: <CAJnByzh4Kzp6-DXXcB06QHSBJpHBKhtDnKUn7R%2BK0A_5VUThyw@mail.gmail.com>
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Hi I write a netmap program that sends packets to the network. my program uses one netmap ring and fills the ring slots with packets. My program needs to do something (action A) after a particular packet (packet P) in the ring slot is sent to the network. so the program tracks the position of the tail point and checks if the tail point has moved across the slot I used to put that packet P. However, I found that the tail pointer may not move forward even seconds after the receiver side got packet P. Sometimes the tail pointer never moves forward until the TX ring is full. I try ioctl(NIOCTXSYNC), however, it cannot 100% solve the problem. My question is that is there a way to make the TX ring empty as early as possible so that I can know when my packet is sent out. or is there another way to know when the packet in the slot is sent to the network/NIC physical queue? I am using Linux 3.16.0-4-amd64. Thanks! Best, Xiaoye
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