IN the case when memory is slow, the rocm-smi outputs this: ======================== ROCm System Management Interface ======================== ================================================================================================ GPU Temp AvgPwr SCLK MCLK PCLK Fan Perf PwrCap SCLK OD MCLK OD GPU% GPU[0] : WARNING: Empty SysFS value: pclk GPU[0] : WARNING: Unable to read /sys/class/drm/card0/device/gpu_busy_percent 0 30.0c N/A 400Mhz 933Mhz N/A 0% auto N/A 0% 0% N/A ================================================================================================ ======================== End of ROCm SMI Log ========================
normal memory speed case gives following: ======================== ROCm System Management Interface ======================== ================================================================================================ GPU Temp AvgPwr SCLK MCLK PCLK Fan Perf PwrCap SCLK OD MCLK OD GPU% GPU[0] : WARNING: Empty SysFS value: pclk GPU[0] : WARNING: Unable to read /sys/class/drm/card0/device/gpu_busy_percent 0 35.0c N/A 400Mhz 1200Mhz N/A 0% auto N/A 0% 0% N/A ================================================================================================ ======================== End of ROCm SMI Log ======================== So there is a difference in MCLK - can this cause such a huge slowdown? -- Lauri On Tue, Mar 12, 2019 at 6:39 PM Kuehling, Felix <felix.kuehl...@amd.com> wrote: > [adding the list back] > > I'd suspect a problem related to memory clock. This is an APU where > system memory is shared with the CPU, so if the SMU changes memory > clocks that would affect CPU memory access performance. If the problem > only occurs when OpenCL is running, then the compute power profile could > have an effect here. > > Laurie, can you monitor the clocks during your tests using rocm-smi? > > Regards, > Felix > > On 2019-03-11 1:15 p.m., Tom St Denis wrote: > > Hi Lauri, > > > > I don't have ROCm installed locally (not on that team at AMD) but I > > can rope in some of the KFD folk and see what they say :-). > > > > (in the mean time I should look into installing the ROCm stack on my > > Ubuntu disk for experimentation...). > > > > Only other thing that comes to mind is some sort of stutter due to > > power/clock gating (or gfx off/etc). But that typically affects the > > display/gpu side not the CPU side. > > > > Felix: Any known issues with Raven and ROCm interacting over memory > > bus performance? > > > > Tom > > > > On Mon, Mar 11, 2019 at 12:56 PM Lauri Ehrenpreis <lauri...@gmail.com > > <mailto:lauri...@gmail.com>> wrote: > > > > Hi! > > > > The 100x memory slowdown is hard to belive indeed. I attached the > > test program with my first e-mail which depends only on > > rocm-opencl-dev package. Would you mind compiling it and checking > > if it slows down memory for you as well? > > > > steps: > > 1) g++ cl_slow_test.cpp -o cl_slow_test -I > > /opt/rocm/opencl/include/ -L /opt/rocm/opencl/lib/x86_64/ -lOpenCL > > 2) logout from desktop env and disconnect hdmi/diplayport etc > > 3) log in over ssh > > 4) run the program ./cl_slow_test 1 > > > > For me it reproduced even without step 2 as well but less > > reliably. moving mouse for example could make the memory speed > > fast again. > > > > -- > > Lauri > > > > > > > > On Mon, Mar 11, 2019 at 6:33 PM Tom St Denis <tstdeni...@gmail.com > > <mailto:tstdeni...@gmail.com>> wrote: > > > > Hi Lauri, > > > > There's really no connection between the two other than they > > run in the same package. I too run a 2400G (as my > > workstation) and I got the same ~6.6GB/sec transfer rate but > > without a CL app running ... The only logical reason is your > > CL app is bottlenecking the APUs memory bus but you claim > > "simply opening a context is enough" so something else is > > going on. > > > > Your last reply though says "with it running in the > > background" so it's entirely possible the CPU isn't busy but > > the package memory controller (shared between both the CPU and > > GPU) is busy. For instance running xonotic in a 1080p window > > on my 4K display reduced the memory test to 5.8GB/sec and > > that's hardly a heavy memory bound GPU app. > > > > The only other possible connection is the GPU is generating so > > much heat that it's throttling the package which is also > > unlikely if you have a proper HSF attached (I use the ones > > that came in the retail boxes). > > > > Cheers, > > Tom > > >
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