Are these functions? Or are you timing expressions in the global scope? -- John On Nov 26, 2014, at 10:28 AM, Colin Lea <[email protected]> wrote:
> Thanks to you both! However, there is still another odd issue. > > These two functions should be the same, but take very different amounts of > time/memory. Both 'T' and 'n_classes' are both of type Int64. > > @time ( > for t = 2:T > for n = 1:n_classes > for j = 1:n_classes > end > end > end > ) > > @time ( > for t = 2:5000 > for n = 1:10 > for j = 1:10 > end > end > end > ) > > elapsed time: 0.063186286 seconds (18190040 bytes allocated) > elapsed time: 0.002261641 seconds (71824 bytes allocated) > > Any insight on this? > > > On Wednesday, November 26, 2014 12:37:12 PM UTC-5, Tim Holy wrote: > Nice job using track-allocation to figure out where the problem is. > > If you really don't want allocation, then you should investigate Devec.jl or > InPlaceOps.jl, or write out these steps using loops to access each element of > those matrices. > > --Tim > > On Wednesday, November 26, 2014 07:55:59 AM Colin Lea wrote: > > I'm implementing an inference algorithm and am running into memory > > allocation issues that are slowing it down. I created a minimal example > > that resembles my algorithm and see that the problem persists. > > > > The issue is that Julia is allocating a lot of extra memory when adding > > matrices together. This happens regardless of whether or not I preallocate > > the output matrix. > > > > Minimal example: > > https://gist.github.com/colincsl/ab44884c5542539f813d > > > > Memory output of minimal example (using julia --track-allocation=user): > > https://gist.github.com/colincsl/c9c9dd86fca277705873 > > > > Am I misunderstanding something? Should I be performing the operation > > differently? > > > > One thing I've played with is the matrix C. The indices are a sliding > > window (e.g. use C[t-10:t] for all t). When I remove C from the equation > > the performance increases by a factor of 2.5. However, it still uses more > > memory than expected. Could this be the primary issue? >
