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Slow performance on samsung S3C6410

Marcin Jędrzejewski
Note: This was originally posted on 18th January 2011 at http://forums.arm.com

Hi,

I'am a software developer and I am trying to port our product to new device. This is Windows CE 6 device with S3C6410 (ARM1176JZF-S) CPU.  The problem is that Q-Bench benchmarks show that this is very fast system but after executing our application it is actually very slow.

I have spend a lot of time profiling various parts of our product, but it shows nothing. Finally what I have found out is that the problem is with the huge code amount. Actually our .exe is ~10MB in size. I have made tests in which I have auto generated huge amounts of code (~200,000 lines of c++ code, VS2005 compiled), and now executing this exe (~1.5MB) on this device shows significant slow down, 8 - 10 times comparing it to other devices (with slower CPUs). This auto generated code does nothing with data, it just executes lots of functions which just increment some variables.

My question is what is the source of problem? From What I know this CPU has  16 KiB instruction cache. Can it be somehow badly configured? I actually have no contact with this device manufacturer. I can only give some hints to its reseler to maybe push information further.

some more info:
Q-Bench Pro - shows that Cache Line == 8, while on other devices it is 32
CeGetCacheInfo - gives below results:
dwL1Flags=0
dwL1ICacheSize=16384
dwL1ICacheLineSize=32
dwL1ICacheNumWays=4
dwL1DCacheSize=16384
dwL1DCacheLineSize=32
dwL1DCacheNumWays=4
dwL2Flags=0
dwL2ICacheSize=0
dwL2ICacheLineSize=0
dwL2ICacheNumWays=0
dwL2DCacheSize=0
dwL2DCacheLineSize=0
dwL2DCacheNumWays=0

Thank You for any help
Martin
Parents
  • Note: This was originally posted on 12th December 2011 at http://forums.arm.com

    TCM is much more faster than external memory, but this only effect code which is placed in TCMs.
    If you doublt that too much cache miss causes the slow performance, you can try to read cache statistic registers if your chip has these registers.
    However, your program would be the same slow on other chip with big caches, because there should still be many cache misses for your program architecture. At least big cache will not do much better than small cache.
    Maybe your external memory should be the real bottleneck. If so, try to optimize timing of the external memory or choose a better ram. :)
    Pls forgive my bad english.
Reply
  • Note: This was originally posted on 12th December 2011 at http://forums.arm.com

    TCM is much more faster than external memory, but this only effect code which is placed in TCMs.
    If you doublt that too much cache miss causes the slow performance, you can try to read cache statistic registers if your chip has these registers.
    However, your program would be the same slow on other chip with big caches, because there should still be many cache misses for your program architecture. At least big cache will not do much better than small cache.
    Maybe your external memory should be the real bottleneck. If so, try to optimize timing of the external memory or choose a better ram. :)
    Pls forgive my bad english.
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