Thx, but, no.
For sparse matrix 10^5,10^4,0.002 is the same . Time for both whiles is
about 48 sek, only 11% o cores is used. I vave 8 cores, 7 sleeps:/
Paul
W dniu sobota, 31 stycznia 2015 15:50:02 UTC+1 użytkownik Sam Kaplan
napisał:
>
> Hi Paul,
>
> If D is allocated on the master, then Julia will need to pass D from the
> master to the workers. I'm guessing that this communication might be more
> expensive than the compute in your loops. It may be useful to take a look
> at distributed arrays in the parallel section of the Julia docs.
>
> Hope it helps.
>
> Sam
>
> On Saturday, January 31, 2015 at 7:38:22 AM UTC-6, paul analyst wrote:
>>
>>
>> Parallel loop, what wroong ? Parallel is slower then normal
>>
>> julia> @time for i=1:l
>> w[i]=var(D[:,i])
>> end
>> elapsed time: 4.443197509 seconds (14074576 bytes allocated)
>>
>>
>> julia> @time ww=@parallel (hcat) for i=1:l
>> var(D[:,i])
>> end
>> elapsed time: 5.287007403 seconds (435449580 bytes allocated, 5.00% gc
>> time)
>> 1x10000 Array{Float64,2}:
>>
>> Paul
>>
>> julia> @time for i=1:l
>> w[i]=var(D[:,i])
>> end
>> elapsed time: 4.331569152 seconds (8637464 bytes allocated)
>>
>> julia> @time ww=@parallel (hcat) for i=1:l
>> var(D[:,i])
>> end
>> elapsed time: 4.908234336 seconds (422121448 bytes allocated, 4.85% gc
>> time)
>> 1x10000 Array{Float64,2}:
>> 0.000703737 0.000731674 0.000582672 0.00080388 0.000759479
>> 0.000402509 0.0007118 0.000989408
>>
>> julia> size(D)
>> (10000,10000)
>>
>
