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wyxxlz
Journeyman III

multiple GPUs problem: same kernel,some devices have low speed?

i use 5970,which have two devicesevice0 and device1;

i run the kernel in single devices model(device0 or device1), need 4093 ms to run the kernel ;

while i run the kernel in multiple devices model,the time need sometime need 4093 ms,some time need 12000ms?

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7 Replies
himanshu_gautam
Grandmaster

wyxxyz,

i am sorry but i think you need to provide some details without which tracking your problem might be very difficult.Please furnish:

1.Ati Stream SDK version

2.Ati Catalyst Driver Version

3.Your OS(Full Name).

4.Your Cpu(is it SSE.2 or higher).

You can also see system requirements for your card at http://www.amd.com/us/products/desktop/graphics/ati-radeon-hd-5000/hd-5970/Pages/ati-radeon-hd-5970-system-requirements.aspx

hope it helps.

himanshu

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thank you first!

my sdk is 2.1,and drivers is 10.4 is multiple GPUs.because sdk2.2 and drivers 10.7 don't support multiple GPUS

os is win7 32 bits and cpu is amd phenom(tm) ii x4 945 processor 3.0ghz

i think  system is support  5970 card.

 

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quadboon
Journeyman III

the hd5970 support in opencl is limited to single-gpu use only, see here: http://developer.amd.com/gpu/atistreamsdk/pages/default.aspx

but from what i have tested it is always limited to the 1st gpu (or whatever i get in devices[0]). if i use devices[1] the behavior differs from card to card, from sys to sys and from sdk/driver version to sdk/driver version. so you can say the behavior is totally unpredictable. for example, some cards do not report any errors but they produce incorrect results while others just segfault.

i hope ATI fixes this soon.

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thank you!

yes the sdk2.2 and drivers 10.7 don't support multiple GPUS.but i found the sdk 2.1 and driver 10.4 is support multiple GPUS.

i test the device[0] and device[1],they work correctly.and in multiple GPUS model  the result is right too!

my question is that the speed is not stabilization.

my test is list.use two 5970 card and in single model the time of kernel used is 4056 ms.

device name :Cypress device version:OpenCL 1.0 ATI-Stream-v2.1(145) device 2 use 12153 ms<- device 3 use 12153 ms<- device 0 use 12153 ms<- device 1 use 16193 ms<- device 0 use 4056 ms device 3 use 4056 ms device 2 use 8081 ms<- device 1 use 4056 ms device 2 use 4056 ms device 3 use 4056 ms device 0 use 4056 ms device 1 use 4056 ms device 2 use 3993 ms device 3 use 4040 ms device 2 use 4056 ms device 0 use 4056 ms

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Originally posted by: wyxxlz thank you!

 

yes the sdk2.2 and drivers 10.7 don't support multiple GPUS.but i found the sdk 2.1 and driver 10.4 is support multiple GPUS.

 

i test the device[0] and device[1],they work correctly.and in multiple GPUS model  the result is right too!

 

my question is that the speed is not stabilization.

 

my test is list.use two 5970 card and in single model the time of kernel used is 4056 ms.

 

There are known issues in mulit-gpu support. These will be fixed in upcoming releases.  we recommend you to use SDK2.2 with latest driver.

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upcoming releases of driver or SDK?

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nou,

ATI SDK version are released every three months.

The best way is to register on amd's site for updates

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