Re: [Gems-users] help with calculating cpu utilization

[Sarath Krishnan <krish091@xxxxxxx>]

Hi Phil

I am also caught on the same situation and any information regarding the collection of statistics of executing only application and no OS instructions would really help.

Thanks,

Sarath

On Tue, Apr 12, 2011 at 12:55 AM, rajath hegde <rajathsh@xxxxxxxxx> wrote:

Thank you Phil.

I understand your explanation. So I would have to change the GEMs code to accomplish the task of calculating the actual utilization of cores. Could you please point me where I can start to look to make these changes?

I appreciate your help.

Thank you,

Rajath Hegde
Washington State University

On Mon, Apr 11, 2011 at 10:44 PM, Philip Garcia <pcgarcia@xxxxxxxx> wrote:

GEMs keeps track of anything running on each CPU, it doesn't matter if it's an actual application, or just a spin loop.  I have more advanced instrumentation in my code to make sure I only count the execution of the applications I want, and not that of the OS.  

When you run 8 threads on 16 cores, 8 cores should be running the idle loop.  Those will likely have better performance than the other cores.  Remember, just because a core is executing instructions doesn't mean it's actually accomplishing work.  Spin loops and much OS code aren't actual work.

Phil

On Apr 12, 2011, at 12:38 AM, rajath hegde wrote:

Hi,

    I have a question on the CPU utilization metrics that we obtain in the stat-dump when I run the simulations. I am simulating a 16 core machine with Solaris. When I run a benchmark program with 8 threads, theoretically only 8 cores will be active and it should be reflected in the statistics. But what I am seeing is that the percentage utilization of all the cores are turning out to be the same and I am not able to understand why it is so.

    The way I am calculating the percentage utilization is: Instruction_executed * cycles_per_instruction / simics_cycles_executed


    Please tell me if I am calculating this the right way or if there is any other way to obtain the accurate CPU utilization? Thanks for the help.

Profiler Stats
--------------
Elapsed_time_in_seconds: 12268
Elapsed_time_in_minutes: 204.467
Elapsed_time_in_hours: 3.40778
Elapsed_time_in_days: 0.141991

Virtual_time_in_seconds: 12227.7
Virtual_time_in_minutes: 203.796
Virtual_time_in_hours:   3.39659
Virtual_time_in_days:    3.39659

Ruby_current_time: 45747823
Ruby_start_time: 1
Ruby_cycles: 45747822

mbytes_resident: 1179.05
mbytes_total: 1570.06
resident_ratio: 0.750955

Total_misses: 47008
total_misses: 47008 [ 11925 1232 135 12440 1457 1596 43 1116 1090 422 24 1120 1862 11037 1453 56 ]
user_misses: 19092 [ 8509 0 0 9068 101 0 0 36 85 0 0 22 73 958 240 0 ]
supervisor_misses: 27916 [ 3416 1232 135 3372 1356 1596 43 1080 1005 422 24 1098 1789 10079 1213 56 ]

instruction_executed: 2848930210 [ 164011837 181023094 182570679 164516946 179675018 180617475 182529107 180468207 180598656 182349335 182613918 180545550 179665794 164810397 180126017 182808180 ]
simics_cycles_executed: 2927873679 [ 182991293 182991293 182991293 182992293 182992293 182992293 182992293 182992292 182992292 182992292 182992292 182992292 182992292 182992292 182992292 182992292 ]
cycles_per_instruction: 0.256926 [ 0.27893 0.252718 0.250576 0.278074 0.254614 0.253286 0.250633 0.253495 0.253312 0.25088 0.250517 0.253387 0.254627 0.277578 0.253977 0.25025 ]
misses_per_thousand_instructions: 0.0165002 [ 0.0727082 0.00680576 0.00073944 0.0756153 0.00810909 0.00883635 0.000235579 0.00618391 0.00603548 0.00231424 0.000131425 0.00620342 0.0103637 0.0669679 0.00806657 0.000306332 ]

--
Thanks,
Rajath Hegde
Washington State University

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--
Thanks,
Rajath Hegde


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