I know very little about hyperthreading, it's not clear that hyperthreading limits performance of a single threaded app to one-half of a core's performance. According to the various gamer benchmarks, hyperthreading introduces some minor overhead on single threaded apps, but it's not 50% penalty (unless, of course, you have a lot of other computations going on at the same time).
Here's a link to benchmarks for single threaded apps http://www.cpubenchmark.net/singleThread.html. What's interesting is that i5's, and even the lowly i3 with a high clock, can outbenchmarks some i7 models. I wonder if this benchmark for single-threaded apps might be a reasonable predictor of glpk performance. Perhaps someone with more expertise could weigh in on this. Jeff On Tue, Feb 5, 2013 at 7:19 AM, Nigel Galloway <[email protected] > wrote: > ** > The results may consistent: > > Core i7 is a quad core processor with HyperThreading, so on Windows XP it > will appear as 8 processors each running at 1.6 Ghz. GLPK can only use one > of these processors so only 12.5% of max. > > Core i5 is dual core with HyperThreading. HyperThreading helps Windows' > threading model but does nothing for Linux. You may find that your Linux > has turned it off. So the i5 looks like 2 porcessors each running at 2.6 > Ghz. GLPK can use 50% of this configuration. > > You may be able to turn off the HyperThreading on the i7 by changing your > BIOS settings. GLPK will then be able to use 25% of max. > > -- > Nigel Galloway > [email protected] > > > On Fri, Feb 1, 2013, at 08:15 AM, Reginald Beardsley wrote: > > Looking at the descriptions I think you're thrashing. Add more memory to > system 1, unless of course there's a typo and that should read "32GiB" > instead of "3GiB" > > --- On *Fri, 2/1/13, Patrik Dufresne <[email protected]>* wrote: > > > From: Patrik Dufresne <[email protected]> > Subject: Re: [Help-glpk] Performance decrease with more powerful computer > To: "Reginald Beardsley" <[email protected]> > Cc: "glpk" <[email protected]> > Date: Friday, February 1, 2013, 9:49 AM > > Hi Reginald, > > Here are the hardware specs i'm comparing. > > System 1 > Windows XP SP2 > Intel Core i5 650 @ 3.20GHz 4 MB Cache3GiB DDR3 1066/1333CPU mark > (according to cpubenchmark.net) : 3154 > Total computation time : 331 sec > > System 2 > Windows XP SP2, Windows 7 64bits, Debian 64bits > Core i7 CPU M 620 @ 2.67GHz 4M Cache4GiB DDR3 1066CPU mark (according to > cpubenchmark.net) : 2718 > Total computation time : 114 secs > > System 3 > Windows XP SP2, Debian 64bits > *Core 2 Duo CPU E6550 @ 2.33GHz **4 MB** Cache L2*4GiB DDR2 800CPU mark > (according to cpubenchmark.net) : 1493 > Total computation time : 172 secs > > I didn't run the benchmark on the computer it self, but the different > between the number is big enough to expect better performance from System > no 1 then System no 3. The total computation time of the problem on > different platform for the same computer are almost identical. (less then > 0.5 sec different). It's safe to assume the platform doesn't have any > impact on the performance. > > I'm using GLPK 4.47 on every platform. On Linux, I did compile it from > source with default flags. For Windows, I pick the pre-compiled version > provided by winglpk project. > > To solve the problem, I need to run GLPK multiple time sequentially. I > may provide dump of every instance of the problem. > > Patrik Dufresne > > On Fri, Feb 1, 2013 at 10:23 AM, Reginald Beardsley > <[email protected]>wrote: > > Could you provide a few details? > > System configurations you're comparing? GLPK version? Compile time > options specified? > > There are a huge number of possibilities. Why do you think the computer > is "more powerful"? > > Reg > > > > --- On *Fri, 2/1/13, Patrik Dufresne <[email protected]>* wrote: > > > From: Patrik Dufresne <[email protected]> > Subject: [Help-glpk] Performance decrease with more powerful computer > To: "GLPK help" <[email protected]> > Date: Friday, February 1, 2013, 8:56 AM > > > Hi, > > I'm using GLPK in one project and the time taken to compute is longer on a > more powerful computer. Does it make any sense to you ? > > I don't have any clues about how to debug it. I would really appreciate > tips to diagnose the problem. > > Patrik Dufresne > -----Inline Attachment Follows----- > > _______________________________________________ > Help-glpk mailing list > [email protected] <http://mc/[email protected]> > https://lists.gnu.org/mailman/listinfo/help-glpk > > > _______________________________________________ > Help-glpk mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/help-glpk > > *_______________________________________________* > Help-glpk mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/help-glpk > > -- http://www.fastmail.fm - A fast, anti-spam email service. > > > _______________________________________________ > Help-glpk mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/help-glpk > >
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