Date: Wed, 10 Jan 1996 20:27:42 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: dennis@etinc.com (dennis) Cc: pb@fasterix.freenix.fr, hackers@freebsd.org Subject: Re: pppd vs ijppp Message-ID: <199601110327.UAA16458@phaeton.artisoft.com> In-Reply-To: <199601110013.TAA00308@etinc.com> from "dennis" at Jan 10, 96 07:13:38 pm
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Geeze, Dennis, and I usually agree with you because of your customer perspective... > A good example is the routing function, which is in the kernel because its > too damn inefficient in user space. PPP routing is a matter of poll retention time vs. transmissability, since the interface PPP uses is generally several orders of magnitude slower than that which it routes to/from. What we are talking about adding is some propagation delay, and even then, it will be on the basis of system loading and user load (which may be zero) that determines if a context switch will actually be to anything other than the idle process. And if it's not, the majority of the protection domain crossing overhead is in the copy in/out, and that's recoverable based on implementation (see previous posting). > Mr kendals example of "lets move tcp out of the kernel" was a good > analogy to the kind of arguments we're getting on this thread. It's not as stupid as it sounds. There are some sound technical reasons why you might want to do this, and if you used mapping tricks (or better, page protection via page anonymity), you might even get better performance out of your applications. I leave you to rummage papers on the topic from ftp.sage.usenix.org. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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