Date: Tue, 3 Oct 1995 17:04:08 -0700 (PDT) From: John Dyson <dyson> To: bde@zeta.org.au (Bruce Evans) Cc: current@freebsd.org Subject: Re: lmbench 1.1.5 vs 2.2-current Message-ID: <199510040004.RAA01398@freefall.freebsd.org> In-Reply-To: <199510032057.GAA30471@godzilla.zeta.org.au> from "Bruce Evans" at Oct 4, 95 06:57:52 am
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>2.2-current seems to be significantly slower than 1.1.5 in many areas. > >These benchmarks were run on the same machine except for a faster disk >and a possibly different L2 cache setting for 2.2-current. > >The faster disk and clustering speed up the file reread benchmark by a >factor of 8. Yep, it is mostly the clustering, and the larger, on-demand, buffer cache. >The local tcp bandwidth is anomalously slow in >2.2-current. No it isn't, the flag that is set before the TCP test in the benchmark really screwing up the results. Either we don't support it correctly, or something strange is happening. >mmap has been tuned for faster access at a cost of >increased setup overhead in 2.2-current. Yep, the amount of time to map a 100-200K (or larger segment) is only a few page fault times. I think that is a very advantageous tradeoff, considering it could take 25-50 page fault times otherwise. >Otherwise, these benchmarks >show unexplained lossages (probably mostly due to vfs bloat) of 10-40% >for 2.2-current. Interesting, the VFS code adds THAT much overhead to the TCP/UDP results??? (Maybe, but I don't think so) I think that a properly ported lmbench, whose results are properly analyzed would show that the new system is much faster in several areas and roughly the same or sometimes a bit slower otherwise. The lmbench summary scripts don't even appear to produce the correct results given the raw data files produced (at least for me.) I always quote the raw data file output -- don't have time or inclination to fix the perl/awk/whatever scripts. John dyson@freebsd.org
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