Date: Thu, 29 Nov 2007 14:22:17 -0800 From: "Matt Reimer" <mattjreimer@gmail.com> To: "Kris Kennaway" <kris@freebsd.org> Cc: freebsd-stable@freebsd.org, Pete French <petefrench@ticketswitch.com> Subject: Re: Also seeing 2 x quad-core system slower that 2 x dual core Message-ID: <f383264b0711291422h1d185f06n4834908f525d8dcf@mail.gmail.com> In-Reply-To: <474F1105.5020708@FreeBSD.org> References: <E1IxklH-000ElU-3w@dilbert.ticketswitch.com> <474F0BDF.8070605@FreeBSD.org> <f383264b0711291106x4b431cbaj56967bb4b8762408@mail.gmail.com> <474F1105.5020708@FreeBSD.org>
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On Nov 29, 2007 11:20 AM, Kris Kennaway <kris@freebsd.org> wrote: > Matt Reimer wrote: > > On Nov 29, 2007 10:58 AM, Kris Kennaway <kris@freebsd.org> wrote: > >> Pete French wrote: > >>> On the dual core processors this takes about 20 seconds. On the quad > >>> cores it takes about 3 minutes! This is true for both the 32 and 64 bit > >>> versions of FreeBSD :-( > >> That almost certainly has nothing to do with how many CPUs your system > >> has, since rm -rf is a single process running on a single core. > > > > I wonder if I'm seeing this too. Running super-smack on a 2 x quad > > core 1.6GHz Dell 1950 I get about 40000 qps, whereas on a 2 x dual > > core 3.0GHz box I've seen 80000 qps. > > Please, let's try to stay focused :) rm -rf has nothing to do with > super-smack and vice versa. It's relevant to $subject. > > Is this expected? > > It is not very surprising. super-smack is not a good SMP benchmark, it > does stupid things like 1-byte I/O, so it is not very scalable nor a > good model of real-world database activity. Accounting for your CPUs > being twice as fast on the dual core, it roughly says that the benchmark > is not scaling beyond 4 CPUs, which is in line with my own observations. Is sysbench a better benchmark? It gives me 2362.99 on the 2 x dual-core box vs 1327.26 on the 2 x quad-core box. Matt
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