Also, it seems that you are multiplexing counters, which also adds more variability. Leonardo
On Thu, Oct 9, 2014 at 2:37 AM, Stephane Eranian <eran...@googlemail.com> wrote: > On Sat, Oct 4, 2014 at 5:54 PM, Hamid Reza Khaleghzadeh > <khaleghza...@gmail.com> wrote: >> Hi list, >> >> I am studying multi-core scheduling and using Linux Perf as a tool for >> comparing different scheduling techniques. So, I usually run a particular >> multi-threaded program with different scheduling and obtain some information >> when the application is running such as cycles, bus-cycles, cache-misses and >> so on. All tests has been done by a Intel Core 2 Duo + Ubuntu 14.04. >> I have encountered with wonderful results. In fact, I ran a parallel program >> two times with different scheduling. While cycles, bus-cycles and miss-rate >> are in test1 are less than those of test2, elapsed time of test1 is more >> than that of test2. I wonder whether you could tell me why this happened? > > I suggest you run your tests for much longer (>60s). Here you don't even > have a second, so you have also capturing overhead. > >> The obtained results were shown at following: >> Test1: >> # started on Sat Oct 4 18:19:55 2014 >> >> >> Performance counter stats for 'system wide' (150 runs): >> >> 1,398,429,117 cycles ( +- 0.13% ) [28.49%] >> 139,439,143 bus-cycles >> ( +- 0.12% ) [28.77%] >> 1,746,982,529 instructions # 1.25 insns per cycle >> ( +- 0.09% ) [43.18%] >> 8,596,204 cache-references >> ( +- 0.45% ) [43.33%] >> 407,815 cache-misses # 4.744 % of all cache refs >> ( +- 1.01% ) [42.79%] >> 15,690,104 r2F77 >> ( +- 0.14% ) [28.51%] >> 1,123,667,581 rC07D >> ( +- 0.21% ) [28.15%] >> >> 0.365244759 seconds time elapsed >> ( +- 0.16% ) >> >> >> Test2: >> # started on Sat Oct 4 18:34:37 2014 >> >> >> Performance counter stats for 'system wide' (150 runs): >> >> 1,403,443,950 cycles ( +- 0.09% ) [28.24%] >> 140,040,576 bus-cycles >> ( +- 0.12% ) [28.70%] >> 1,752,745,189 instructions # 1.25 insns per cycle >> ( +- 0.10% ) [43.13%] >> 8,557,756 cache-references >> ( +- 0.43% ) [43.35%] >> 412,481 cache-misses # 4.820 % of all cache refs >> ( +- 1.16% ) [43.01%] >> 15,728,789 r2F77 >> ( +- 0.16% ) [28.53%] >> 1,119,849,348 rC07D >> ( +- 0.18% ) [28.21%] >> >> 0.363744760 seconds time elapsed >> ( +- 0.14% ) >> >> ------------------------------------------------------------------------------ >> Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer >> Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports >> Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper >> Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer >> http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk >> _______________________________________________ >> perfmon2-devel mailing list >> perfmon2-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/perfmon2-devel >> > > ------------------------------------------------------------------------------ > Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer > Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports > Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper > Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer > http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk > _______________________________________________ > perfmon2-devel mailing list > perfmon2-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/perfmon2-devel ------------------------------------------------------------------------------ Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
