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: 103376,78a1af350f4cf4b X-Google-Attributes: gid103376,public From: "Robert I. Eachus" Subject: Re: Win2000 has 63,000 'defects' Date: 2000/03/04 Message-ID: <38C09E9F.2C752521@earthlink.net>#1/1 X-Deja-AN: 592966270 Content-Transfer-Encoding: 7bit References: <38A989B7.2D4D6B56@maths.unine.ch> <2000Feb15.143333.1@eisner> <2000Feb15.155800.1@eisner> <150220001931201946%emery@grebyn.com> <88hbpp$j4i$1@news.btv.ibm.com> <88ma3c$p6a$1@nnrp1.deja.com> <2000Feb21.071938.1@eisner> X-Accept-Language: en,pdf Content-Type: text/plain; charset=us-ascii X-Complaints-To: abuse@earthlink.net X-Trace: newsread1.prod.itd.earthlink.net 952147288 63.24.56.224 (Fri, 03 Mar 2000 21:21:28 PST) Organization: The MITRE Corporation MIME-Version: 1.0 NNTP-Posting-Date: Fri, 03 Mar 2000 21:21:28 PST Newsgroups: comp.lang.ada Date: 2000-03-04T00:00:00+00:00 List-Id: Larry Kilgallen wrote: > If one considers the possibility it is an _estimate_, based on typical > industry figures, the very thought of only 1.5 defects per KLOC is out > of the question. Some people I know use 5 defects per KLOC for code > that has been revised and 10 defects per KLOC for "new" code. Reports > indicate that Windows 2000 has a lot of new code. When I was at Stratus, there was a very common understanding. I think I heard it "officially" expressed at more than one engineering meeting, but never saw any underlying documentation. Basicly it goes like this, if your (OS, real-time, compiler, transaction processing, etc.) code has more than one bug per thousand lines, it could never be made robust enough to ship. If your code has less than one bug per 10,000 lines, it will cost less to get it to 1 bug per million lines than to get the bug 1 per 1000 lines code to one bug per 2000. Of course, it cost at least twice as much to write 1 bug per 10,000 line code than to write one bug per thousand lines code. But writing the buggier code at Stratus for any critical code (read any part of the OS or the tools to build it) was worthless. So we had to spend the time up front to get it right. The key measure of quality was the MBTF during beta test for new OS versions, and we aimed for about one year when we released. MBTF was much higher on operational systems, since the customers would run the beta test versions only on development machines. By the time the customers applications were fielded, they had run into most of the OS bugs that they could on the development systems. In any case, we never got to one bug per million lines, but we were well above one per 10000 lines of fielded code. (Most of this code was writen in PL/I. C was only used on I/O cards with less than 64K of memory.) So there are really two styles of programming. One, which may or may not be fine for computer games, etc., relies on debugging quality in. The other relies on building it in in the first place. Most Ada programmers are used to the second style, which is why we seldom (if ever!) use a debugger.