Return to BSD News archive
Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!convex!convex!news.duke.edu!eff!news.kei.com!ddsw1!panix!not-for-mail From: tls@panix.com (Thor Lancelot Simon) Newsgroups: comp.unix.bsd Subject: Re: BSD for the Sun386i Date: 14 May 1994 04:16:32 -0400 Organization: PANIX Public Access Internet and Unix, NYC Lines: 58 Message-ID: <2r21d0$pls@panix2.panix.com> References: <2qcljn$gqt@norm.eng.gtefsd.com> <2qk8uf$kok@panix2.panix.com> <Boyt076.dysonj@delphi.com> <2r16me$363@keyhole.ucsd.edu> NNTP-Posting-Host: panix2.panix.com In article <2r16me$363@keyhole.ucsd.edu>, Eric Dorman <eld@keyhole.ucsd.edu> wrote: >Hi all. >>> >>>Uh...almost, at best. >>> >>>Can we say, "sio and hacks on the tty code", kids? >>> >>>There, I knew we could. >> >>Yes, FreeBSD uses ring-buffers instead of clists -- can we say theoretically >>faster... I thought you could... > >[deleted] > >>BTW, sorry, for the smart-alecky response. I personally would prefer >>that we (FreeBSD) used clists, but we dont. I would rather throw away >>an unmeasurable performance advantage for compatibility. But thats the >>breaks!!! >>John >>dyson@implode.root.com > >Many moons ago (85?) we had some Intel Multibus I 80286 boxes running Xenix 3.0. >We used them to do simple editing and playback of seismic data recorded on >4-track reel-to-reel tape. When playing back, the data came out at >(i forget) I think 8x real time, which worked out to be about 19100bits/sec >sustained rate. The Intel machines were able to pickup the stream without >dropping a bit and have some umpf left over. Heh > >Then Intel, in its infinite wisdom, replaced the clist system with 256byte >ring buffers. Now we could *barely* able to keep up with the stream; doing >anything caused the ring buffer to fill up and data got lost. Awwwwwwwwww! >Editing serial data was a *real* pain; searching for sync words, hacking >bits back in, updating time. ARGH! Take a look at SunOS zs driver performance under 3.X and 4.X. You don't see many characters dropped due to ring buffer overflow on a 3/50 doing 38.4 on one serial port; but a 4/60 or /65 drops a *lot* of characters under those conditions. Of course, the ring buffers on the 3.5 can't overflow, since it uses clists. :-) Yeah, there are a lot of other differences between the two drivers, like STREAMS-ness, and ugly recycled bits of asm from the 3.X zs driver that don't fit well into the 4.X one. But ring buffers aren't the be-all and end-all of serial driver speed. In fact, I'd love to be convinced that they're any kind of substantial win over clists at all. >Moral: >Not all applications are (were :) ) created equal. Nor all implementations, either. -- Thor Lancelot Simon tls@panix.COM But as he knew no bad language, he had called him all the names of common objects that he could think of, and had screamed: "You lamp! You towel! You plate!" and so on. --Sigmund Freud