Date: Wed, 5 Feb 2003 10:20:50 +0100 From: "Jens Wiggers" <jens.wiggers@ruhr-uni-bochum.de> To: <hackers@FreeBSD.ORG>, <freebsd-net@FreeBSD.ORG> Subject: Correlation between CPU load and network usage Message-ID: <000001c2ccf7$dfcdcc70$1d01a8c0@iis2>
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Hi, I'm using two FreeBSD machines in an small switched network. One of them blows out tcp packets as fast as possible for five seconds. The other machine just receives the packets and does nothing else. What I see is that for short packets the senders CPU load is just 100 percent, but for larger packets the senders CPU load drops down rapidly. >From the applications point of view the data to send gets into the socket buffer and via tcp_output, ip_output and ether_output into the interface buffer. The rest of work is done by the interrupt handler of the network controller. Therefore the application returns from the socket send syscall and calls it again. So where is sparetime for the CPU in this cycle? Any help would be appreciated. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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