How to get correct global variable with jupyter's timeit?











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One first cell I have this:



from numba import cuda
@cuda.jit
def thread_counter_safe(global_counter):
cuda.atomic.add(global_counter, 0, 1) # Safely add 1 to offset 0 in global_counter array


On the next cell I have this:



global_counter = cuda.to_device(np.array([0], dtype=np.int32))
thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())

global_counter = cuda.to_device(np.array([0], dtype=np.int32))
%timeit thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())


Output of this second cell is something like this:



Should be 4096: [4096]
10000 loops, best of 3: 118 µs per loop
Should be 4096: [168390656]


Jupyter Notebook's timeit carries the global_counter accross its iteration test. How do it get it to give back global_counter correctly?










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  • 1




    you would need to reset the global_counter to zero as part of the function that you are running timeiton. You can't safely/easily do that from the thread_counter_safe cuda kernel, but you could def a new function that resets the global_counter to zero and then calls thread_counter_safe, and run timeit on that.
    – Robert Crovella
    Nov 9 at 14:48










  • Got it. A wrapper function would do, but still prefer some flag or parameter when calling timeit.
    – biocyberman
    Nov 9 at 15:11















up vote
0
down vote

favorite












One first cell I have this:



from numba import cuda
@cuda.jit
def thread_counter_safe(global_counter):
cuda.atomic.add(global_counter, 0, 1) # Safely add 1 to offset 0 in global_counter array


On the next cell I have this:



global_counter = cuda.to_device(np.array([0], dtype=np.int32))
thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())

global_counter = cuda.to_device(np.array([0], dtype=np.int32))
%timeit thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())


Output of this second cell is something like this:



Should be 4096: [4096]
10000 loops, best of 3: 118 µs per loop
Should be 4096: [168390656]


Jupyter Notebook's timeit carries the global_counter accross its iteration test. How do it get it to give back global_counter correctly?










share|improve this question




















  • 1




    you would need to reset the global_counter to zero as part of the function that you are running timeiton. You can't safely/easily do that from the thread_counter_safe cuda kernel, but you could def a new function that resets the global_counter to zero and then calls thread_counter_safe, and run timeit on that.
    – Robert Crovella
    Nov 9 at 14:48










  • Got it. A wrapper function would do, but still prefer some flag or parameter when calling timeit.
    – biocyberman
    Nov 9 at 15:11













up vote
0
down vote

favorite









up vote
0
down vote

favorite











One first cell I have this:



from numba import cuda
@cuda.jit
def thread_counter_safe(global_counter):
cuda.atomic.add(global_counter, 0, 1) # Safely add 1 to offset 0 in global_counter array


On the next cell I have this:



global_counter = cuda.to_device(np.array([0], dtype=np.int32))
thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())

global_counter = cuda.to_device(np.array([0], dtype=np.int32))
%timeit thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())


Output of this second cell is something like this:



Should be 4096: [4096]
10000 loops, best of 3: 118 µs per loop
Should be 4096: [168390656]


Jupyter Notebook's timeit carries the global_counter accross its iteration test. How do it get it to give back global_counter correctly?










share|improve this question















One first cell I have this:



from numba import cuda
@cuda.jit
def thread_counter_safe(global_counter):
cuda.atomic.add(global_counter, 0, 1) # Safely add 1 to offset 0 in global_counter array


On the next cell I have this:



global_counter = cuda.to_device(np.array([0], dtype=np.int32))
thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())

global_counter = cuda.to_device(np.array([0], dtype=np.int32))
%timeit thread_counter_safe[64, 64](global_counter)
print('Should be %d:' % (64*64), global_counter.copy_to_host())


Output of this second cell is something like this:



Should be 4096: [4096]
10000 loops, best of 3: 118 µs per loop
Should be 4096: [168390656]


Jupyter Notebook's timeit carries the global_counter accross its iteration test. How do it get it to give back global_counter correctly?







jupyter-notebook numba






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edited Nov 9 at 15:10









talonmies

59k17128195




59k17128195










asked Nov 9 at 10:58









biocyberman

2,55422135




2,55422135








  • 1




    you would need to reset the global_counter to zero as part of the function that you are running timeiton. You can't safely/easily do that from the thread_counter_safe cuda kernel, but you could def a new function that resets the global_counter to zero and then calls thread_counter_safe, and run timeit on that.
    – Robert Crovella
    Nov 9 at 14:48










  • Got it. A wrapper function would do, but still prefer some flag or parameter when calling timeit.
    – biocyberman
    Nov 9 at 15:11














  • 1




    you would need to reset the global_counter to zero as part of the function that you are running timeiton. You can't safely/easily do that from the thread_counter_safe cuda kernel, but you could def a new function that resets the global_counter to zero and then calls thread_counter_safe, and run timeit on that.
    – Robert Crovella
    Nov 9 at 14:48










  • Got it. A wrapper function would do, but still prefer some flag or parameter when calling timeit.
    – biocyberman
    Nov 9 at 15:11








1




1




you would need to reset the global_counter to zero as part of the function that you are running timeiton. You can't safely/easily do that from the thread_counter_safe cuda kernel, but you could def a new function that resets the global_counter to zero and then calls thread_counter_safe, and run timeit on that.
– Robert Crovella
Nov 9 at 14:48




you would need to reset the global_counter to zero as part of the function that you are running timeiton. You can't safely/easily do that from the thread_counter_safe cuda kernel, but you could def a new function that resets the global_counter to zero and then calls thread_counter_safe, and run timeit on that.
– Robert Crovella
Nov 9 at 14:48












Got it. A wrapper function would do, but still prefer some flag or parameter when calling timeit.
– biocyberman
Nov 9 at 15:11




Got it. A wrapper function would do, but still prefer some flag or parameter when calling timeit.
– biocyberman
Nov 9 at 15:11

















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