Date: Mon, 27 Jun 2005 16:17:34 -0500 From: Sam Pierson <samuel.pierson@gmail.com> To: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Accurate/Fine-grained timing of latency in atheros drivers Message-ID: <d9204e4c0506271417513b7f58@mail.gmail.com>
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Hey guys, In a current project, I need to find out exactly how long it takes to send a 802.11 packet and how much time is spent in the following stages: send time - time spent constructing message, including context switches and other delays and the time it takes to transfer the message to the network card. access time - delay which we experience waiting to access the transmitting channel. Normally this would include the RTS and CTS queuing signals, but for this application, I have to disable them. Is it possible that no t= ime is spent waiting here, if I have disabled the whole CSMA scheme on the hardware level? propagation time - how long it takes to get to the receiver, once it has le= ft our card receive time - how long it takes for the receiving network card to get the= =20 message and notify the host that it has something to read. Am I going to have to put in hardware interrupts to time these events or=20 are such tools already available? =20 -Sam
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