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update host async
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Michael Wolfe



Joined: 19 Jan 2010
Posts: 42

PostPosted: Wed Aug 08, 2012 3:40 pm    Post subject: Reply with quote

In the first place, we have to link against the driver API, not the runtime API.
In the second place, these aren't callbacks, these would require polling or waiting for the event to finish, neither of which is asynchronous from the host code.
We are looking at reimplementing the async implementation and perhaps getting rid of the auxiliary thread, but we're not sure about the effect on performance. The real problem is that true async data copies require pinned host memory, and the interface for pinning host data is not composable, such as when the user program as well as the OpenACC runtime may try to pin and unpin the same memory.
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Alexey A. Romanenko



Joined: 17 Feb 2012
Posts: 36

PostPosted: Fri Feb 22, 2013 12:59 am    Post subject: Reply with quote

Hi guys,

I'm working now with 13.1 and 13.2. It looks like situation with overlapping data transfer with kernel execution was not changed significantly. Could you please comment future of this feature.

WBR,
Alexey
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mkcolg



Joined: 30 Jun 2004
Posts: 6218
Location: The Portland Group Inc.

PostPosted: Fri Feb 22, 2013 9:22 am    Post subject: Reply with quote

Hi Alexey,

Sorry, nothing has change with regards to the synchronization behaviour. The same challenges outlined by Michael still exist and they are still investigating solutions. There is no time frame on when this can be improved.

- Mat
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