cannot lower Memory clock on Titan X

Accelerated Computing CUDA CUDA Programming and Performance
1

I am running experiments where I want to evaluate the performance of applications with reduced memory clock rates. I am trying to use nvdia-smi to do this. Although I am able to reduce the SM clock to the desired level, the memory clock always appears to max out at 5005.

My CUDA driver is 9.0

(ada)% sudo nvidia-smi -ac 810,607
Applications clocks set to "(MEM 810, SM 607)" for GPU 00000000:84:00.0
All done.

(ada)% nvprof -u ms --system-profiling on ~/BabelStream/cuda-stream 
BabelStream
Version: 3.3
Implementation: CUDA
Running kernels 100 times
Precision: double
Array size: 268.4 MB (=0.3 GB)
Total size: 805.3 MB (=0.8 GB)
==16946== NVPROF is profiling process 16946, command: BabelStream/cuda-stream

=16946== System profiling result:
Device "TITAN X (Pascal) (0)"
                                         Count         Avg         Min         Max
SM Clock (MHz)                      21      562.43      139.00      607.00
Memory Clock (MHz)              21     4145.19      405.00     5005.00
Temperature (C)                     42       27.29       26.00       28.00
 Power (mW)                          42    70258.55    15929.00    83478.00
 Fan (%)                                
21       23.00       23.00       23.00
2

Do you have persistence mode set?

If not, your application clocks setting might not be maintained:

[url]https://devblogs.nvidia.com/increase-performance-gpu-boost-k80-autoboost/[/url]

also, have you checked to make sure that your requested settings 810,607 are included in the SUPPORTED_CLOCKS ?

You may also want to update your GPU driver to the latest for your GPU

3

Thanks. The persistence mode had initially tripped me up. But I do have it set (I have one GPU in the system)

(ada)% sudo nvidia-smi -pm 1 
Persistence mode is already Enabled for GPU 00000000:84:00.0.
All done.

SUPPORTED_CLOCKS shows 810,607 is valid (at least the way I read it)

(ada)% nvidia-smi -q -d SUPPORTED_CLOCKS

==============NVSMI LOG==============

Timestamp                           : Wed May 30 16:44:53 2018
Driver Version                      : 384.111

Attached GPUs                       : 1
GPU 00000000:84:00.0
    Supported Clocks
        Memory                      : 5005 MHz
            Graphics                : 1911 MHz
...
...
        Memory                      : 810 MHz
            Graphics                : 1911 MHz
            Graphics                : 1898 MHz
            Graphics                : 1885 MHz
            Graphics                : 1873 MHz
...
...
            Graphics                : 607 MHz
            Graphics                : 594 MHz
            Graphics                : 582 MHz
            Graphics                : 569 MHz
            Graphics                : 556 MHz