Troubleshooting • Re: Pi5 8GB memory bandwidth significantly lower than Pi5 4GB

Code:

pi@pi5-4:~ $ rpi-eeprom-update BOOTLOADER: up to date   CURRENT: Tue 30 Jul 14:25:46 UTC 2024 (1722349546)    LATEST: Wed  5 Jun 15:41:49 UTC 2024 (1717602109)   RELEASE: beta (/lib/firmware/raspberrypi/bootloader-2712/beta)            Use raspi-config to change the release.

Code:

-------------------------------------------------------------STREAM version $Revision: 5.10 $-------------------------------------------------------------This system uses 8 bytes per array element.-------------------------------------------------------------Array size = 10000000 (elements), Offset = 0 (elements)Memory per array = 76.3 MiB (= 0.1 GiB).Total memory required = 228.9 MiB (= 0.2 GiB).Each kernel will be executed 10 times. The *best* time for each kernel (excluding the first iteration) will be used to compute the reported bandwidth.-------------------------------------------------------------Your clock granularity/precision appears to be 1 microseconds.Each test below will take on the order of 53961 microseconds.   (= 53961 clock ticks)Increase the size of the arrays if this shows thatyou are not getting at least 20 clock ticks per test.-------------------------------------------------------------WARNING -- The above is only a rough guideline.For best results, please be sure you know theprecision of your system timer.-------------------------------------------------------------Function    Best Rate MB/s  Avg time     Min time     Max timeCopy:           12305.7     0.013012     0.013002     0.013038Scale:          11677.2     0.013724     0.013702     0.013762Add:            10266.5     0.023419     0.023377     0.023556Triad:          11690.9     0.020550     0.020529     0.020591-------------------------------------------------------------Solution Validates: avg error less than 1.000000e-13 on all three arrays-------------------------------------------------------------

Code:

-------------------------------------------------------------STREAM version $Revision: 5.10 $-------------------------------------------------------------This system uses 8 bytes per array element.-------------------------------------------------------------Array size = 10000000 (elements), Offset = 0 (elements)Memory per array = 76.3 MiB (= 0.1 GiB).Total memory required = 228.9 MiB (= 0.2 GiB).Each kernel will be executed 10 times. The *best* time for each kernel (excluding the first iteration) will be used to compute the reported bandwidth.-------------------------------------------------------------Your clock granularity/precision appears to be 1 microseconds.Each test below will take on the order of 54233 microseconds.   (= 54233 clock ticks)Increase the size of the arrays if this shows thatyou are not getting at least 20 clock ticks per test.-------------------------------------------------------------WARNING -- The above is only a rough guideline.For best results, please be sure you know theprecision of your system timer.-------------------------------------------------------------Function    Best Rate MB/s  Avg time     Min time     Max timeCopy:           11301.8     0.014184     0.014157     0.014244Scale:          11446.6     0.014009     0.013978     0.014059Add:             9949.4     0.024161     0.024122     0.024202Triad:          11538.0     0.020824     0.020801     0.020841-------------------------------------------------------------Solution Validates: avg error less than 1.000000e-13 on all three arrays-------------------------------------------------------------