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Xref: sserve comp.os.386bsd.misc:3963 comp.os.386bsd.questions:14227 comp.os.linux.development:18652 comp.os.linux.misc:28777 sci.electronics:83250 Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!yarrina.connect.com.au!warrane.connect.com.au!godzilla.zeta.org.au!not-for-mail From: bde@zeta.org.au (Bruce Evans) Newsgroups: comp.os.386bsd.misc,comp.os.386bsd.questions,comp.os.linux.development,comp.os.linux.misc,sci.electronics Subject: Re: 16550 detection Date: 5 Nov 1994 07:19:50 +1100 Organization: Kralizec Dialup Unix Sydney - +61-2-837-1183, v.32bis v.42bis Lines: 30 Message-ID: <39e516$5s3@godzilla.zeta.org.au> References: <m0r2XH0-000MhFC@kitana> <JKH.94Nov1231956@freefall.cdrom.com> NNTP-Posting-Host: localhost.zeta.org.au In article <JKH.94Nov1231956@freefall.cdrom.com>, Jordan K. Hubbard <jkh@freefall.cdrom.com> wrote: >In article <m0r2XH0-000MhFC@kitana> kitana!sysop@caprica.com (JL Gomez) writes: > > I've e-mail someone using a BOCA 2016 using 8 ports at 115K what their > load was on the CPU. > > He replied 3% under Linux. Says alot about the serial driver. > >Or a lot about creative statistics. 8 ports doing 115.2K continuous. It says that the 8 ports weren't going at full speed or that the the overhead wasn't measured accurately. The ISA bus overhead alone is more than 10 times that: (8 ports) * (2 directions) * (11520 cps) = 230400 cps * (about 1.25 usec to to read each character from the bus) = 230400 usec/sec = 23% overhead + (8 ports) * (1 direction) * 11520 * (about 1.25 usec to read the error status for each char input) = 34.5% overhead >I'm not knocking Linux, but I'd distrust claims like this under FreeBSD >just as highly. People are very often prone to make them after the On a 486DX2/66 with 16550's, FreeBSD-1.1.5 and Linux-1.1.12 and later versions have almost exactly the same serial load, 2.5 to 3 times the minimum calculated above. -- Bruce Evans bde@zeta.org.au