Structure problem between host/kernel

Accelerated Computing CUDA CUDA Programming and Performance
1

Hello,

I have data structures on the host side that looks like this. ( I show the relevant parts ). Why I need to have it like this is a long story but I think I need to keep this structure.

struct Bar {

    double ind[NR_OF_INPUTS - 2];

    int date;

    int time;

};

struct Week {

	int numBars;

	struct Bar* bars;

};

struct ThreadWeeksHolder {

	int nr_weeks_per_thread;

	struct Week* week;

};

On the host side I then have a an array like this “ThreadWeeksHolder kernel_thread_weeks_holder[32];” Which is filled with data that is read from a file. Everything works fine so far. My problem comes when I try to get this data to the kernel and keep the structure layout. I want to be able to use the same structure on the kernel. This turned out to be way much more complicated then I first thought.

My plan was to try to build a structure on the host with the gpu-pointers received from cudaMalloc and then copy them over to the graphic card but I can’t really get it to work. The problem is that the pointers that I receive from cudaMalloc makes no sense on the host side if I try to dereference them so to speak.( which totally makes sense ). So for example if I have a line like this

cudaMalloc((void**)&kernel_thread_weeks_holder[1].week[2].bars, threadWeeksHolder[i].week[j].numBars*sizeof(struct Bar));

Then I have a pointer kernel_thread_weeks_holder[i].week[j].bars that points to the appropriate place in the GPU-memory. But after that I also will need a “relationship” between kernel_thread_weeks_holder[i].week and kernel_thread_weeks_holder[i].week[j].bars so to speak. But on the host things get messed up then for me. Hope you can understand what I mean and what my problem is.

Anyone have any suggestions or hints how I can solve this problem?

2

Never dereference device pointers on the host. You have the corresponding host pointer in the original structure you are trying to replicate on the device, so use that one.

I believe that some advice i recently gave in another thread also applies here though.

3

Thanks! I read through the other thread as well. I think I got some ideas now, gonna try out some things tomorrow.