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[boxerab]

I've turned on out of order queues on my project running on HD 7700.

This significantly improves performance, I highly recommend it!

Only caveat is that you have to manage kernel sequence yourself, using events.

My question: which AMD cards support out of order queues?  Also, is this feature purely on

the driver side, or is there silicon required to support it? 

Thanks!

[thesmith]

Out of order queues device-side queues is part of the OpenCL standard since 1.0. Every GPU should support it AFAIK. For host-side it depends on the implementation. I know of one device that does not! Altera clearly states in its programming guide that its runtime does not support such queues.

[dipak]

As per OpenCL spec, supporting out-of-order queue is not a mandatory feature. So, I guess, if you pass the out-of-order flag during command queue creation, the implementation may ignore this flag if out-of-order is not supported by the platform.

[dipak]

AFAIK, out-of-order host-side queues are not currently supported on AMD platform, but out-of-order device-side queues are supported. However, certain devices have hardware support which can simultaneously handle multiple commands from multiple queues. Hence, they can provide a significant performance boost if many independent tasks are enqueued concurrently to the device via multiple opencl queues.

Anyway, as you mentioned, you can see a performance improvement if you turns on the out-of-order mode. Its really interesting. Could you please be more explicit about the commands you enqueued and how? Meanwhile I'll check with some experienced folks for more details.

Regards,

[thesmith]

I was mistaken on device-side vs host-side. I think the OP talks about the the former.

[boxerab · Accepted solution]

Thanks, Dipak. Yeah, this turned out to be wishful thinking. On closer inspection, the out of order flag is ignored; makes not difference.

[boxerab]

Are there plans to support host-side out of order queues?  Seems to me this would be easier

than doing device side out of order queues, something we already have implemented.

Thanks,

Aaron

[pinform]

None that I know of.

zypo - I've branched the newer questions into a new thread: Device queues.

--Prasad