From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,9c86eb13dd395066 X-Google-Attributes: gid103376,public From: Jim Balter Subject: Re: CRC in Ada? Date: 1997/03/11 Message-ID: <3325DF35.3BDF@netcom.com>#1/1 X-Deja-AN: 224778946 References: <1997Mar2.220652@nova.wright.edu> <331d3cf9.1190126@news.logica.co.uk> <1997Mar5.083233.1@eisner> <1997Mar5.131846.1@eisner> <5fmo1k$adm@mulga.cs.mu.OZ.AU> <3324A613.812@netcom.com> Organization: JQB Enterprises X-NETCOM-Date: Tue Mar 11 2:41:48 PM PST 1997 Newsgroups: comp.lang.ada Date: 1997-03-11T14:41:48-08:00 List-Id: Robert Dewar wrote: > > Jim Balter quoted me and replied > > < interpretation show a total *lack* of experience. If the tests are > coded properly so that the buffer accesses aren't optimized out of > existence, you will see about a 3:1 difference in user cpu time between > the getchar version and the read version, solely as a consequence of the > getchar macro requiring more instructions. Exactly the same number of > system calls are made, as anyone who attempts to *understand* the > issue instead of indulging in silly sophistry will know. If you then > do, say, 20 instructions worth of processing per character, the ratio > is 23:21. *Big* difference, like you'd expect. Feh.>> > > Well if there is one thing I am certainly not guilty of, it is lack of > experience :-) > > But actually Jim, you have your quotes confused. I never said there > were a different number of systems calls, of course not! I said exactly > the opposite. "You cannot make such statements (the standard IO lbrary of C definitely does IO in blocks). The standard speaks only of interfaces, not of implementation, there is nothing in the standardized interface that requires IO to be done in blocks. This may be an implementation characterstic of some or even most or even all current implementations, but it is NOT a fundamental property of the standard IO library. " And there has been other material in which you have implied that multiple system calls might be involved. > I am not quite sure what you mean by the measurements being misleading, > they are measuring exactly what they purport to be measuring. It is > possible to draw incorrect conclusions from these measurements, but > they only mislead those who wish to be mislead! What a foolish thing to say. Take a course in philosophy of science. --