Getting weird OpenCL error messages and a 0 H/s benchmark result when mining. What could be wrong?

Question

I am trying to mine Ethereum using geth and ethminer using a single AMD Radeon HD 7850 with 2 GB of memory on Ubuntu 16.04. I installed the latest recommended driver, ran geth --maxpeers 0 (to avoid syncing with the blockchain) and then tried to benchmark my setup using ethminer -G -M. I get a few possible OpenCL error messages when trial 1 is beginning, then that phase ends with a hashrate of 0, same for trial 2, 3, 4 and 5. After the fifth trial, the program just keeps running, but nothing is happening. But have a look for yourself:

$ ethminer -G -M
[OPENCL]:Found suitable OpenCL device [Pitcairn] with 1692704768 bytes of GPU memory
  ◇  23:12:24.160|ethminer  #00004000…
Benchmarking on platform: { "platform": "AMD Accelerated Parallel Processing", "device": "Pitcairn", "version": "OpenCL 1.2 AMD-APP (2348.3)" }
Preparing DAG...
Warming up...
  ℹ  23:12:24.160|gpuminer0  workLoop 0 #00000000… #00000000…
  ℹ  23:12:24.160|gpuminer0  Initialising miner...
Trial 1... [OPENCL]:Using platform: AMD Accelerated Parallel Processing
[OPENCL]:Using device: Pitcairn(OpenCL 1.2 AMD-APP (2348.3))
[OPENCL]:clCreateCommandQueue(-6)
[OPENCL]:clEnqueueWriteBuffer(-36)
0
Trial 2... 0
Trial 3... 0
Trial 4... 0
Trial 5... 0

I tried reinstalling the graphics driver and ethminer. Mining without the -G parameter works just fine, but is way too slow, of course. I searched for people having the same problem and there are a few, but they didn't find any solution or the thread just died. I hope someone here can help!

Answer 1

You can set these environment variables:

export GPU_MAX_HEAP_SIZE=100

export GPU_SINGLE_ALLOC_PERCENT=100

export GPU_FORCE_64BIT_PTR=1

export GPU_USE_SYNC_OBJECTS=1

export GPU_MAX_ALLOC_PERCENT=100

then start ethminer.

Answer 2

try restarting or close all background services. it works for me whenever i start boot up or restart the computer.

1.restart 2.as soon as the computer boot in windows click the miner. dont wait for the other app on start up comes before you.