View Full Version : cl_mem and devices inside a context...

07-26-2009, 04:59 AM
I have a basic doubt about cl_mem thing..

Say, I have a context made out of 2 CUDA GPUs. Now I create a cl_mem structure on top of it...

Later, I issue a clEnqueueRead... request to read that buffer...

Now, how much of that buffer comes from device 0 and how much comes from device 1?

07-27-2009, 09:41 AM
viewtopic.php?f=28&t=1927 (http://www.khronos.org/message_boards/viewtopic.php?f=28&t=1927)

07-29-2009, 06:46 AM
pmdinu, Thanks for your reply.

I still have some questions...

Now, I understand that cl_mem buffer is associated with both devices...in the context. Fine.

So, when I spawn a kernel, and if the kernel that runs on both the devices update this buffer -- what happens??

WIll it not result in confusion?

Glad if some1 could help me out here. Thanks!

07-29-2009, 03:01 PM
Hi Sarnath,
clEnqueueRead has a one to one mapping with a device trough the clQueue object.


07-29-2009, 10:29 PM

You opened my eyes.. I did not realize that command queue is device specific... Hmm....

Interesting... So, it is logically like dividing a buffer across multiple devices...

Okay, Thanks for the info!!!

That REALLY helped!

Best Regards,