Re: [Starpu-devel] Performance decreasing by adding empty tasks

[Xavier Lacoste <xavier.lacoste@inria.fr>]

I runned with gprof on a smaller test case : my read only array is 329968 
integers.
I can understand that most of the time is spent with data management, but 
that's all i can say...

I attached the gprof output.

Attachment: gprof2.out
Description: Binary data

Le 16 févr. 2012 à 16:35, Samuel Thibault a écrit :

> Xavier Lacoste, le Thu 16 Feb 2012 16:28:54 +0100, a écrit :
>>      This is not good either, I though that as the buffer is read-only on 
>> all tasks that uses it, it wouldn't cost much to manage but when I look to 
>> my Gantt diagram I spend much time "PushingOutput". Why do StarPU have to 
>> push that read-only buffer ?
> 
> Just for the record: it should not ever be doing that for a read-only
> buffer. Unless something is perhaps keeping the spinlock of the data for
> a long time for some reason. Maybe using gprof to know where most of the
> cpu time is spent would help.
> 
> Samuel