Date: Mon, 4 Jun 2007 14:16:04 -0400 From: Kris Kennaway <kris@obsecurity.org> To: Tim Daneliuk <tundra@tundraware.com> Cc: freebsd-questions@freebsd.org Subject: Re: New != Faster Message-ID: <20070604181604.GB28548@rot13.obsecurity.org> In-Reply-To: <466451CA.6020108@tundraware.com> References: <466451CA.6020108@tundraware.com>
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On Mon, Jun 04, 2007 at 12:54:18PM -0500, Tim Daneliuk wrote: > In the course of trying to work through some problems with a new MOBO, > I did some speed test which I found sort of surprising: > > Old System > ---------- > > Dual PIII 600Mhz w/768K Mem and Mylex RAID 5 with old 9G SCSI drived > FBSD 4.11-Stable > Writing a 1G file to /dev/null with dd reports about 26MB/sec > > New System > ---------- > > Pentium D 3.2GHz w/2G Mem and SATA Drive reported running at SATA-150 > FBSD 6.2-STABLE > Writing a 2G file to /dev/null with dd reports about 50MB/sec > > > So ... the new system should be much faster all the way around, right? > Hmmmm, not necessarily so. 'buildworld' is only about 17% faster on the > new machine v. the old. I would think that with way faster processors > and twice the disk bandwidth I would have seen far reduced buildworld > times. So, I decided to check a known fast machine. The results: > > Procs Mem dd Read OS > buildworld > > > Old 2 PIII @600Mhz 768K 26M/sec 4.11-stable/SMP 50-60 > min > New Pent D (2 core)@3.2GHz 2G 50M/sec 6.2-stable/SMP 40-50 > min > Fast 2 Xeon @3GHz 3G 130M/sec 4.11-stable/SMP 8 > min > > > So, now I'm confused. These are all lightly loaded systems but the > buildworld time does not scale even approximately by either CPU or > I/O performance. What the heck is going on, I wonder? It is possible, > I suppose that the "New" machine does not have SMP running properly on it, > though 'top' shows two CPUs working away. Is the difference in speed > attributable to 4.11 being faster than 6.2? Unfortunately, I cannot > get 4.11 to boot on the "New" machine - it does not like the hardware > for some reason claiming: > > RTC BIOS diagnostic error 80<clock battery> > > Even after I change the RTC battery on the mobo. > > Strange ... any input appreciated. This comparison is 100% bogus. 4.11 and 6.2 are vastly different (the latter builds all sorts of different code, and uses a *different compiler* that is slower in compiling the code). When trying to compare something, you have to compare the *same* thing, or it's meaningless. Kris
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