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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!howland.reston.ans.net!europa.eng.gtefsd.com!MathWorks.Com!news.kei.com!news.byu.edu!news.mtholyoke.edu!nic.umass.edu!opine.cs.umass.edu!merlot!doyle From: doyle@merlot.cs.umass.edu (Jim Doyle) Newsgroups: comp.os.386bsd.development Subject: FreeBSD 1.1G - SLIP performance problems Date: 29 Apr 1994 12:00:38 GMT Organization: CS Dept., Umass-Amherst Lines: 54 Message-ID: <2pqst6$g4s@opine.cs.umass.edu> Reply-To: doyle@cs.umass.edu NNTP-Posting-Host: merlot X-Newsreader: TIN [version 1.2 PL0] I've encountered receive-side throughput problems with the SLIP implementation in the latest 1.1Gamma FreeBSD release. It appears that the interface drops or misses a significant amount of the traffic presented to it on the receive side, . There are no throughput or reliability problems when the SLIP interface is transmitting data. These observations were mmade while I was performance testing an 8088 running PCRoute as an Ethernet <-> SLIP rouThis is what I was using to do the test: 386 PC (FreeBSD) <----> PCRoute <---> DEC 3100 (Ultrix 4.2) * The 386PC (386dx40) has a 16550A on the port used for the SLIP interface. It is connected to the PCRoute box useing a hardwired null-modem SLIP link. The SLIP link ran at 38400 bps, I did not try 57600. * The PCRouter is an 8MHz 8088 with a 16550A UART and a 3com 503 Ethernet board running Vance Morrison's PCRoute software. * The DEC3100 is connected to the router over Ethernet. - FTP traffic coming from the FreeBSD box loaded the SLIP link fully with no stalls in data transfer. I observed 3.4 KB/s. - Telnet from the DEC3100 to the FreeBSD box on the chargen service port also loaded the line up, with data streaming at a steady and continuous rate to the telnet client. - FTP traffic from the DEC into the FreeBSD box died quickly. The SLIP link had alot of dead time, it appeared that traffic was being dropped. - From the FreeBSD box, if I telnetted to the chargen port on the 3100, data streamed in at an extremely slow rate... It took about 2 minutes to fill the screen with the test pattern on the FreeBSD box, whereas in the opposite direction of traffic, it would take about hbout a second to fill a screen with the test patter. - I am convinced the router is not dropping the traffic... If I remove the FreeBSD box and use a Sun SPARC 1+ (SunOS 4.1.3, CSLIP 2.7) at 38400, the router can forward traffic at full wirespeed (SLIP) in both directions without hesitation in the telnet to the chargen port, or degraded FTP throughput. Overall, I am satisfied with PCRoute as a cheap bridge solution. If anyone can suggest modifcations to my test environment, or tweaks to the FreeBSD code, to improve performance then let me know and I would be glad to try retesting. -- Jim Doyle <doyle@cs.umass.edu>