Tensorflow allocating all memory for any program - tensorflow

Question

OS Platform and Distribution (e.g., Linux Ubuntu 16.04): linux Ubuntu 16.04
TensorFlow installed from (source or binary): binary
TensorFlow version (use command below): v1.4.0-rc1
Python version: 3.5.5
CUDA/cuDNN version: CUDA 8.0 / cuDNN 6
GPU model and memory: nvidia gtx 1080
I am new to Tensorflow. So this could easily be some silly installation error that I don't see.
I open python to test TF installation:
import tensorflow as tf
from tensorflow.python.client import device_lib
print(device_lib.list_local_devices())
Resulting in:
I tensorflow/core/platform/cpu_feature_guard.cc:137] Your CPU supports instructions that this TensorFlow binary was not compiled to use: SSE4.1 SSE4.2 AVX
2018-04-11 21:39:44.830140: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1030] Found device 0 with properties:
name: GeForce GTX 1080 major: 6 minor: 1 memoryClockRate(GHz): 1.8475
pciBusID: 0000:01:00.0
totalMemory: 7.92GiB freeMemory: 78.94MiB
2018-04-11 21:39:44.830178: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1120] Creating TensorFlow device (/device:GPU:0) -> (device: 0, name: GeForce GTX 1080, pci bus id: 0000:01:00.0, compute capability: 6.1)
2018-04-11 21:39:44.832231: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 78.94M (82771968 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.834394: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 71.04M (74494976 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.835825: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 63.94M (67045632 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.837560: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 57.55M (60341248 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.839233: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 51.79M (54307328 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.841757: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 46.61M (48876800 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.843632: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 41.95M (43989248 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.845588: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 37.76M (39590400 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.847229: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 33.98M (35631360 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.849278: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 30.58M (32068352 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
2018-04-11 21:39:44.850967: E tensorflow/stream_executor/cuda/cuda_driver.cc:936] failed to allocate 27.52M (28861696 bytes) from device: CUDA_ERROR_OUT_OF_MEMORY
[name: "/device:CPU:0"
device_type: "CPU"
memory_limit: 268435456
locality {
}
incarnation: 6037705122138393497
, name: "/device:GPU:0"
device_type: "GPU"
memory_limit: 82771968
locality {
bus_id: 1
}
incarnation: 11403601020071115295
physical_device_desc: "device: 0, name: GeForce GTX 1080, pci bus id: 0000:01:00.0, compute capability: 6.1"
]

Answer 1

Supposing your question is "Why does Tensorflow allocate all available GPU memory even though much less memory would be enough for my program?", then the answer is that they do this to reduce GPU memory fragmentation. You can change this default behavior with some settings like config.gpu_options.allow_growth and config.gpu_options.per_process_gpu_memory_fraction to make Tensorflow less memory hungry at the expense of allowing some potential memory fragmentation to occur. Detailed explanation in the Tensorflow Programmer's Guide Using GPU chapter.