Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!ames!amdahl!amdcad!tim From: tim@amdcad.AMD.COM (Tim Olson) Newsgroups: comp.lang.c Subject: Re: Dhrystones Message-ID: <19425@amdcad.AMD.COM> Date: Thu, 3-Dec-87 19:38:29 EST Article-I.D.: amdcad.19425 Posted: Thu Dec 3 19:38:29 1987 Date-Received: Tue, 8-Dec-87 00:59:08 EST References: <3368@rosevax.Rosemount.COM> <5096@ccv.bbn.COM> Reply-To: tim@amdcad.UUCP (Tim Olson) Organization: Advanced Micro Devices Lines: 27 Keywords: C, performance, useful In article <5096@ccv.bbn.COM> kgregory@ccv.bbn.com.BBN.COM (Keith D. Gregory) writes: | In article <3368@rosevax.Rosemount.COM> richw@rosevax.Rosemount.COM (Rich Wagenknecht) writes: | >Could somemone tell me what a 'Dhrystone' (<-sp.?) is? | >Why is it used so often to evaluate compiler performance? | >Is it a good overall indicator of compiler peformance? | | 1 - Compare different compilers for a given machine. I find this to be very | useful - although there are certainly many factors contributing to the | efficiency of compiled code, I've found that Dhrystone figures give a | fairly accurate comparison of two compilers (as I see it, if a compiler | writer makes efficient integer procesing code, the system calls will | probably be efficient too). I just wanted to add the caveat that Dhrystone has some major problems as a benchmark when you are talking about very good optimizing compilers. There exists quite a lot of "dead code" in Dhrystone (expressions which aren't ever used) which good compilers can optimize totally away. This isn't the case with real-world code. At the high-end, all you are comparing with Dhrystone is how much code your compiler threw away vs another compiler ;-) Dhrystone is also heavily weighted towards string operations (strcpy & strcmp can total 35% - 40% of the runtime). -- Tim Olson Advanced Micro Devices (tim@amdcad.amd.com)