On Tue, 2006-01-24 at 18:25 +0900, MAEDA Naoaki wrote:
> Hi all,
>
> I've taken some benchmark results of cpurc-v0.3-2615 in order to
> measure its overhead and the accuracy of enforced CPU share.
>
> 1) Overhead measurement with lat_ctx -s 0 in various # of processes
>
> The overhead is between -0.02 to +0.07 microseconds.
> It is quite small.
>
> # Vanilla 2.6.15 2.6.15+cpurc-v0.3 Diff [us]
> ---------------------------------------------------------
> 2 0.51 0.52 +0.01
> 4 0.58 0.6 +0.02
> 8 0.71 0.71 0.0
> 16 0.72 0.72 0.0
> 32 0.73 0.72 -0.01
> 64 0.78 0.85 +0.07
> 128 1.08 1.06 -0.02
> 256 1.85 1.89 +0.04
> ----------------------------------------------------------
These numbers look pretty good. Are you doing multiple runs of lat_ctx
-s 0 at the same number of processes in order to get some idea of how
noisy the difference is? Perhaps these values are within the noise
margin.
> 2) CPU share enforcement test with kernbench
>
> User and Sys time are almost constant in every case.
> On the other hand, enforcing shares are _roughly_ equal to
> the percentages of CPU consumed by kernbench. It is not too bad,
> but further investigation is needed.
>
> Share[%] Elaps[s] User[s] Sys[s] CPU[%]
> ----------------------------------------------
> 100 321.9 295.1 19.7 97.0
> 90 325.4 293.5 19.5 95.8
> 80 345.9 293.2 19.7 90.0
> 70 392.6 293.3 19.6 79.2
> 60 466.0 293.6 19.8 66.8
> 50 583.0 296.4 19.8 53.8
> 40 725.3 297.7 19.6 43.2
> 30 925.2 299.6 19.4 34.0
> 20 1458.2 301.5 19.3 21.2
> 10 2595.5 303.4 20.0 12.0
> ----------------------------------------------
>
> - One class for running kernbench was defined and various
> share was set to the class.
>
> - kernbench -M against 2.6.15 kernel source
>
> - Five infinity loop programs were running on the default_class
> at the same time. Otherwise, kernbench was able to consume
> all of the CPU resource.
Nice results!
Out of curiosity, do you know why 1 infinite loop was not sufficient as
a load?
Cheers,
-Matt Helsley
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