Date: Sun, 25 Nov 2007 15:58:43 -0600 (CST) From: Stephen Montgomery-Smith <stephen@math.missouri.edu> To: Kip Macy <kip.macy@gmail.com> Cc: binto <binto@triplegate.net.id>, Girwatson@freebsd.org, freebsd-hackers@freebsd.org, Roman Divacky <rdivacky@freebsd.org>, Robert Watson <rwatson@freebsd.org> Subject: Re: Before & After Under The Giant Lock Message-ID: <20071125155702.F6960@cauchy.math.missouri.edu> In-Reply-To: <b1fa29170711251322t2e44881pd2595a3a2387f4fa@mail.gmail.com> References: <474830F9.90305@zirakzigil.org> <6eb82e0711240638g2cc1e54o1fb1321cafe8ff9f@mail.gmail.com> <1188.202.127.99.4.1195957922.squirrel@webmail.triplegate.net.id> <20071125110116.U63238@fledge.watson.org> <20071125143546.V6583@cauchy.math.missouri.edu> <20071125211807.GA12250@freebsd.org> <20071125151941.I6583@cauchy.math.missouri.edu> <b1fa29170711251322t2e44881pd2595a3a2387f4fa@mail.gmail.com>
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On Sun, 25 Nov 2007, Kip Macy wrote: >>>> >>>> I just want to add my 2 cents, that my recent experience with FreeBSD MP >>>> has been extremely positive. I tend to use highly CPU bound MP programs, >>>> typically lots and lots of floating point operations. It used to be that >>>> Linux beat FreeBSD hands down - now FreeBSD seems to have a slight edge! >>>> Basically my program runs about twice as fast when I run two threads as >>>> opposed to one - I cannot see doing any better than that! >>> >>> pure computation does not need kernel operations most of the time.. ie. >>> multi-threading kernel wont help much ;) >>> >> >> Yes, I know. But something else was also done to FreeBSD, perhaps fine >> tuning with the scheduler, that did bring about massive improvements. >> > > I assume you're using ULE. Jeff has gone to great lengths to take > cache affinity into account. This may be what you are benefiting from. No, I'm using 4BSD under FreeBSD 7.0. But I just tried it with ULE under FreeBSD 8.0 (Witnesses and invariants switched off), and the speed marginally slower, but only by 2% or so.
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