Messages in this thread | | | Date | Thu, 29 Mar 2012 10:43:35 -0700 | From | Tim Bird <> | Subject | Re: [RFC] Android Logger vs. Shared Memory FIGHT! |
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On 03/29/2012 10:09 AM, Daniel Walker wrote: > John Stultz commented on how gettimeofday() is more accurate that what > is needed. Logger actually uses a less accurate, and faster, method of timing. > The time isn't exactly apples to apples, my shared memory example is actually > using a slower clock compared to logger.
OK - that's interesting. > >> >> Tests were 60 seconds. I presume there were multiple runs and these are >> averages. Can you provide the number of runs and the standard deviation for >> each set? > > > Test cases were 600 seconds (10 minutes) .. There were three runs. > Here's the raw data, all in bytes per second: > > X86: > Logger TSC = 70072480.0, 83911562.7, 78610971.8 > Shared Memory TSC = 460262336.0, 454204684.1, 457050682.2 > > Logger ACPI_PM = 75523320.0, 81615111.9, 81588600.2 > Shared Memory ACPI_PM = 29688532.0, 28211029.2, 28225661.6 > > > ARM: > Logger = 6985508.0, 5827587.3, 7034293.7 > Shared Memory = 12371886.7, 18362639.9, 15274489.3
> You can feel free to compute the standard deviation if you wish.
Here are the std deviations:
x86-logger-tsc: 7.4% x86-shmem-tsc: 0.5% x86-logger-ACPI_PM: 3.6% x86-shmem-ACPI_PM: 2.4% ARM-logger: 8.4% ARM-shmem: 15.9%
Performance ratios: x86-shmem-tsc/x86-logger-tsc -> 5.9 x86-shmem-ACPI_PM/x86-logger-ACPI_PM -> 0.36 ARM-shem/ARM-logger -> 2.3
It would be nice to understand why the ARM numbers are not more consistent. I'll try to take a look at this next week.
Thanks for the data.
I recently started work on my own performance test suite for logger. I'm taking the approach of simulating log insertions based on log timings from a sampled device, and measuring cost per message. I'm not sure when I'll finish it, but I'll post results when I have them. -- Tim
============================= Tim Bird Architecture Group Chair, CE Workgroup of the Linux Foundation Senior Staff Engineer, Sony Network Entertainment =============================
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