Date: Thu, 15 Dec 2005 20:05:38 +0000 From: Pete French <petefrench@ticketswitch.com> To: PeterJeremy@optushome.com.au Cc: stable@freebsd.org Subject: Re: kernel cpu entries Message-ID: <E1EmzMA-0006Rw-U4@dilbert.firstcallgroup.co.uk> In-Reply-To: <20051215182250.GO77268@cirb503493.alcatel.com.au>
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> I can't see anything in the kernel source code to explain it. Since > you don't mention actual times, is the difference statistically > significant? (see src/tools/tools/ministat) Ministat says: Difference at 95.0% confidence The second set are always smaller than the first set no matter how many times I run it, so it is repeatable. I only wrote down a few of the raw results, but here are a set of three outputs from time (real, user, system) for i686 alone and i586+i686. i686: 496.26 857.54 43.05 501.00 858.03 42.40 517.04 857.90 42.91 i586+i686: 483.70 852.70 51.77 484.93 853.54 50.60 489.26 855.23 46.82 It is a shame I didnt do any without the -j2 on. I suspect that it would show a slowdown, as the user+system times are always lower on the i686 on its own. But when running in parallel you actually get a speedup in elapsed time, even though you are seeing a slowdown on each processor individually. So does adding in i586 somehow increase the potential for parallelism somehow ? Thats the only thing I can think of.... -pete.
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