Using parfor

2012 4 27
2 个回答
回答已采纳
3 次查看（30 天）

0 个投票

Hi I successfully implemented a parfor loop in Matlab. However on my computer which has 4 cores I am not getting the improvement in computation time I expected to get. When I go to the task manager and check the CPU usage it rarely goes over 25% which is the same as before the parfor loop What could be the problem?

请先登录，再回答此问题。

 采纳的回答

Thomas
Thomas 2012-4-27

0 个投票

What kind of problem have you set up using parfor.. a general fact about the Parallel Computing Toolbox is that the parallel tasks have to be pretty intensive/expensive in order for parallelization be effective..
If your computation is trivial then you might not get the speedup you expect.. Not a lot more can be said without looking at what code you have parallelized.
Also, is your machine quad core or a two core hyperthreaded which would show up as 4 virtual cores?

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Peter
Peter 2012-4-27
Hi thanks for your reply,
My processor is an Intel(R) Core(TM)2 Quad CPU Q8200 @2.33GHz.
Yes the tasks are pretty heavy.I use bintprog with a hundreds or thousands of variables that take a while to compute and other computationally expensive stuff.
I define the parfor this way on MATLAB 7.5.0(R2007b):
parfor (r=1:m_dash,4)
... end
Is that the correct way?

请先登录，再进行评论。

更多回答（1 个）

Edric Ellis
Edric Ellis 2012-5-2

0 个投票

One thing to check - have you opened MATLABPOOL before issuing PARFOR? You need to do this in each MATLAB session to make the extra workers available. I.e.
matlabpool open local 4

类别

在 帮助中心 和 File Exchange 中查找有关 Parallel Computing Toolbox 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by