Date: Mon, 18 Sep 2000 18:11:53 -0700 From: Lars Eggert <larse@ISI.EDU> To: hackers@freebsd.org Subject: implementing idle-time networking Message-ID: <39C6BD59.4C1AFD02@isi.edu>
next in thread | raw e-mail | index | archive | help
This is a cryptographically signed message in MIME format. --------------ms0AF875C3CEAC113E286FF61E Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hi, as part of my thesis research, I'm implementing something similar to the POSIX idle-time CPU scheduler for other resource types, one being network I/O. The basic idea is to substitute two-level queues for the standard ones. I'm seeing some unexpected things (explained below), but let me first outline what I'm doing exactly: 1. I extend the ifnet structure to contain a second ifqueue, for idle-time traffic; and also declare a new flag for mbufs, to indicate whether network idle-time processing should be done or not. 2. In sosend(), I check if the sending process is running at a POSIX idle-time priority. If so, I set the idle-time flag in the mbuf. 3. In ether_output_frame(), I check if the idle-time flag is set on an mbuf, and if so, enqueue it in the interface's idle-time queue (default queue otherwise.) 4. In xl_start() (my onboard chip happens to use the xl driver), I first check the default queue for any mbufs ready to send. If there are none, I try the idle-time queue. If an mbuf could be dequeued from either queue, I continue with normal outbound processing (have mbuf be picked up by NIC). Unfortunately, this scheme does not work. Some first experiments have shown that idle-time network performance is practically identical to regular-priority. I measured it going from a slower (10Mb/s) to a faster (100Mb/s) host through a private switch, so the NIC should be the bottleneck (the processors are both 800Mhz PIII). The new code is in fact executed, I have traced it heavily. Closer inspection revealed that both the ifnet ifqueues as well as the driver transmission chain are always empty upon enqueue/dequeue. Thus, even though my fancy queuing code is executed, it has no effect, since there never are any queues. Can someone shed some light on if this is expected behavior? Wouldn't that mean that as packets are being generated by the socket layer, they are handed down through the kernel to the driver one-by-one, incurring at interrupt for each packet? Or am I missing the obvious? Thanks, Lars -- Lars Eggert <larse@isi.edu> Information Sciences Institute http://www.isi.edu/larse/ University of Southern California --------------ms0AF875C3CEAC113E286FF61E Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIIIIwYJKoZIhvcNAQcCoIIIFDCCCBACAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3DQEHAaCC BfQwggLYMIICQaADAgECAgMDIwUwDQYJKoZIhvcNAQEEBQAwgZQxCzAJBgNVBAYTAlpBMRUw EwYDVQQIEwxXZXN0ZXJuIENhcGUxFDASBgNVBAcTC0R1cmJhbnZpbGxlMQ8wDQYDVQQKEwZU aGF3dGUxHTAbBgNVBAsTFENlcnRpZmljYXRlIFNlcnZpY2VzMSgwJgYDVQQDEx9QZXJzb25h bCBGcmVlbWFpbCBSU0EgMTk5OS45LjE2MB4XDTAwMDgyNDIwMzAwOFoXDTAxMDgyNDIwMzAw OFowVDEPMA0GA1UEBBMGRWdnZXJ0MQ0wCwYDVQQqEwRMYXJzMRQwEgYDVQQDEwtMYXJzIEVn Z2VydDEcMBoGCSqGSIb3DQEJARYNbGFyc2VAaXNpLmVkdTCBnzANBgkqhkiG9w0BAQEFAAOB jQAwgYkCgYEAz1yfcNs53rvhuw8gSDvr2+/snP8GduYY7x7WkJdyvcwb4oipNpWYIkMGP214 Zv1KrgvntGaG+jeugAGQt0n64VusgcIzQ6QDRtnMgdQDTAkVSQ2eLRSQka+nAPx6SFKJg79W EEHmgKQBMtZdMBYtYv/mTOcpm7jTJVg+7W6n04UCAwEAAaN3MHUwKgYFK2UBBAEEITAfAgEA MBowGAIBBAQTTDJ1TXlmZkJOVWJOSkpjZFoyczAYBgNVHREEETAPgQ1sYXJzZUBpc2kuZWR1 MAwGA1UdEwEB/wQCMAAwHwYDVR0jBBgwFoAUiKvxYINmVfTkWMdGHcBhvSPXw4wwDQYJKoZI hvcNAQEEBQADgYEAi65fM/jSCaPhRoA9JW5X2FktSFhE5zkIpFVPpv33GWPPNrncsK13HfZm s0B1rNy2vU7UhFI/vsJQgBJyffkLFgMCjp3uRZvBBjGD1q4yjDO5yfMMjquqBpZtRp5op3lT d01faA58ZCB5sxCb0ORSxvXR8tc9DJO0JIpQILa6vIAwggMUMIICfaADAgECAgELMA0GCSqG SIb3DQEBBAUAMIHRMQswCQYDVQQGEwJaQTEVMBMGA1UECBMMV2VzdGVybiBDYXBlMRIwEAYD VQQHEwlDYXBlIFRvd24xGjAYBgNVBAoTEVRoYXd0ZSBDb25zdWx0aW5nMSgwJgYDVQQLEx9D ZXJ0aWZpY2F0aW9uIFNlcnZpY2VzIERpdmlzaW9uMSQwIgYDVQQDExtUaGF3dGUgUGVyc29u YWwgRnJlZW1haWwgQ0ExKzApBgkqhkiG9w0BCQEWHHBlcnNvbmFsLWZyZWVtYWlsQHRoYXd0 ZS5jb20wHhcNOTkwOTE2MTQwMTQwWhcNMDEwOTE1MTQwMTQwWjCBlDELMAkGA1UEBhMCWkEx FTATBgNVBAgTDFdlc3Rlcm4gQ2FwZTEUMBIGA1UEBxMLRHVyYmFudmlsbGUxDzANBgNVBAoT BlRoYXd0ZTEdMBsGA1UECxMUQ2VydGlmaWNhdGUgU2VydmljZXMxKDAmBgNVBAMTH1BlcnNv bmFsIEZyZWVtYWlsIFJTQSAxOTk5LjkuMTYwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGB ALNpWpfU0BYLerXFXekhnCNyzRJMS/d+z8f7ynIk9EJSrFeV43theheE5/1yOTiUtOrtZaeS Bl694GX2GbuUeXZMPrlocHWEHPQRdAC8BSxPCQMXMcz0QdRyxqZd4ohEsIsuxE3x8NaFPmzz lZR4kX5A6ZzRjRVXjsJz5TDeRvVPAgMBAAGjNzA1MBIGA1UdEwEB/wQIMAYBAf8CAQAwHwYD VR0jBBgwFoAUcknCczTGVfQLdnKBfnf0h+fGsg4wDQYJKoZIhvcNAQEEBQADgYEAa8ZZ6TH6 6bbssQPY33Jy/pFgSOrGVd178GeOxmFw523CpTfYnbcXKFYFi91cdW/GkZDGbGZxE9AQfGuR b4bgITYtwdfqsgmtzy1txoNSm/u7/pyHnfy36XSS5FyXrvx+rMoNb3J6Zyxrc/WG+Z31AG70 HQfOnZ6CYynvkwl+Vd4xggH3MIIB8wIBATCBnDCBlDELMAkGA1UEBhMCWkExFTATBgNVBAgT DFdlc3Rlcm4gQ2FwZTEUMBIGA1UEBxMLRHVyYmFudmlsbGUxDzANBgNVBAoTBlRoYXd0ZTEd MBsGA1UECxMUQ2VydGlmaWNhdGUgU2VydmljZXMxKDAmBgNVBAMTH1BlcnNvbmFsIEZyZWVt YWlsIFJTQSAxOTk5LjkuMTYCAwMjBTAJBgUrDgMCGgUAoIGxMBgGCSqGSIb3DQEJAzELBgkq hkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTAwMDkxOTAxMTE1M1owIwYJKoZIhvcNAQkEMRYE FLxb5IyRKZ08HeztzbqAkLd6k5COMFIGCSqGSIb3DQEJDzFFMEMwCgYIKoZIhvcNAwcwDgYI KoZIhvcNAwICAgCAMAcGBSsOAwIHMA0GCCqGSIb3DQMCAgFAMA0GCCqGSIb3DQMCAgEoMA0G CSqGSIb3DQEBAQUABIGASrieifrAPe54qFUHcXJctSCzOCxO0qKbc1R4spynHunoxcX+rqmo f8rtmKzXAazErAUZhMxp4HN27m2nBI8WuwQ1GcwpK/I7dJQrXubCyW83cbWoooV1dgp0epfA rXad0QJ0yrIP1gM6o/vA2qatTc0HtzFlaK2jRqo69qSmMRE= --------------ms0AF875C3CEAC113E286FF61E-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?39C6BD59.4C1AFD02>