Don't see any transfers on NVLINK with NCCL all_sum test












0















With the following code (uses tensorflow.contrib.nccl.all_sum), I expected to see bytes being transferred over NVLINK.
In reality, I don't.



from tensorflow.contrib.nccl import all_sum 

with tf.device('/gpu:0'):
a = tf.get_variable(
"a", initializer=tf.constant(1.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:1'):
b = tf.get_variable(
"b", initializer=tf.constant(2.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:0'):
summed_node = all_sum([a, b])
sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=True,
log_device_placement=True))

init = tf.global_variables_initializer()
sess.run(init)

with tf.device('/gpu:0'):
summed = sess.run(summed_node)


My machine is an AWS instance of p3.8xlarge. My understanding is, this configuration supports NVLINK.



The execution is fine but when I use nvidia-smi nvlink -g 0 -i 0 the link Tx/Rx counts are zero.










share|improve this question




















  • 1





    My removal of the CUDA tag wasn't an accident. This isn't a CUDA programming question and should not be tagged as one

    – talonmies
    Nov 28 '18 at 21:26











  • removed CUDA tag

    – auro
    Nov 28 '18 at 21:39
















0















With the following code (uses tensorflow.contrib.nccl.all_sum), I expected to see bytes being transferred over NVLINK.
In reality, I don't.



from tensorflow.contrib.nccl import all_sum 

with tf.device('/gpu:0'):
a = tf.get_variable(
"a", initializer=tf.constant(1.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:1'):
b = tf.get_variable(
"b", initializer=tf.constant(2.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:0'):
summed_node = all_sum([a, b])
sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=True,
log_device_placement=True))

init = tf.global_variables_initializer()
sess.run(init)

with tf.device('/gpu:0'):
summed = sess.run(summed_node)


My machine is an AWS instance of p3.8xlarge. My understanding is, this configuration supports NVLINK.



The execution is fine but when I use nvidia-smi nvlink -g 0 -i 0 the link Tx/Rx counts are zero.










share|improve this question




















  • 1





    My removal of the CUDA tag wasn't an accident. This isn't a CUDA programming question and should not be tagged as one

    – talonmies
    Nov 28 '18 at 21:26











  • removed CUDA tag

    – auro
    Nov 28 '18 at 21:39














0












0








0








With the following code (uses tensorflow.contrib.nccl.all_sum), I expected to see bytes being transferred over NVLINK.
In reality, I don't.



from tensorflow.contrib.nccl import all_sum 

with tf.device('/gpu:0'):
a = tf.get_variable(
"a", initializer=tf.constant(1.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:1'):
b = tf.get_variable(
"b", initializer=tf.constant(2.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:0'):
summed_node = all_sum([a, b])
sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=True,
log_device_placement=True))

init = tf.global_variables_initializer()
sess.run(init)

with tf.device('/gpu:0'):
summed = sess.run(summed_node)


My machine is an AWS instance of p3.8xlarge. My understanding is, this configuration supports NVLINK.



The execution is fine but when I use nvidia-smi nvlink -g 0 -i 0 the link Tx/Rx counts are zero.










share|improve this question
















With the following code (uses tensorflow.contrib.nccl.all_sum), I expected to see bytes being transferred over NVLINK.
In reality, I don't.



from tensorflow.contrib.nccl import all_sum 

with tf.device('/gpu:0'):
a = tf.get_variable(
"a", initializer=tf.constant(1.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:1'):
b = tf.get_variable(
"b", initializer=tf.constant(2.0, shape=(args.dim, args.dim)))

with tf.device('/gpu:0'):
summed_node = all_sum([a, b])
sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=True,
log_device_placement=True))

init = tf.global_variables_initializer()
sess.run(init)

with tf.device('/gpu:0'):
summed = sess.run(summed_node)


My machine is an AWS instance of p3.8xlarge. My understanding is, this configuration supports NVLINK.



The execution is fine but when I use nvidia-smi nvlink -g 0 -i 0 the link Tx/Rx counts are zero.







tensorflow cudnn nvlink






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share|improve this question













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edited Nov 28 '18 at 21:38







auro

















asked Nov 28 '18 at 20:02









auroauro

496519




496519








  • 1





    My removal of the CUDA tag wasn't an accident. This isn't a CUDA programming question and should not be tagged as one

    – talonmies
    Nov 28 '18 at 21:26











  • removed CUDA tag

    – auro
    Nov 28 '18 at 21:39














  • 1





    My removal of the CUDA tag wasn't an accident. This isn't a CUDA programming question and should not be tagged as one

    – talonmies
    Nov 28 '18 at 21:26











  • removed CUDA tag

    – auro
    Nov 28 '18 at 21:39








1




1





My removal of the CUDA tag wasn't an accident. This isn't a CUDA programming question and should not be tagged as one

– talonmies
Nov 28 '18 at 21:26





My removal of the CUDA tag wasn't an accident. This isn't a CUDA programming question and should not be tagged as one

– talonmies
Nov 28 '18 at 21:26













removed CUDA tag

– auro
Nov 28 '18 at 21:39





removed CUDA tag

– auro
Nov 28 '18 at 21:39












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