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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!arclight.uoregon.edu!mr.net!newshub.tc.umn.edu!fu-berlin.de!irz401!orion.sax.de!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc,comp.arch,comp.benchmarks Subject: Re: benchmarking discussion at Usenix? Date: 8 Jan 1997 02:25:47 GMT Organization: Private BSD site, Dresden Lines: 41 Message-ID: <5av0jb$aus@uriah.heep.sax.de> References: <5am7vo$gvk@fido.asd.sgi.com> <5aonle$8lr@uriah.heep.sax.de> <32D18190.369A6C81@informatik.tu-muenchen.de> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: knews 0.9.6 X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:33652 comp.arch:62185 comp.benchmarks:18662 Bernd Paysan <paysan@informatik.tu-muenchen.de> wrote: > > > . osbench > > Only curious: what are the goals for this? > > OS code has somewhat different characteristic from user code. If you That's been my basic question, yes. I wasn't aware that the typical usage pattern of kernel code differs that much from user code. > But I wonder if porting to userland gives a good benchmark. Part of the > OS workload game is the switch between user land and kernel land for > each OS call. Well, i think the effect of this is often overestimated. Funny enough, lmbench proved the opposite. :-) lmbench clearly shows that Linux has a much faster syscall handling than other systems, but still (and no, i'm not fighting for 10 or 20 % here), it's not _way_ faster than other systems under identical conditions. The conclusion from this is that syscall overhead is most likely not the typical bottle- neck. > Another part is exception and interrupt handling. Hmm. This can't be expressed in a benchmark, hardly. OTOH, if the system keeps reasonable statistics, the effect of interrupt and exception handling should be forseeable. I estimate this being less than ~ 10 % of the total time on a modern machine. > Advantages over the real thing: much more portable, and better to get a > stable basis Yes. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)