---------- Forwarded message ----------
From: Eric J Korpela <[email protected]>
Date: Tue, Jul 28, 2009 at 6:17 PM
Subject: Re: [boinc_dev] credit goals
To: Martin <[email protected]>


On Thu, Jul 23, 2009 at 7:07 AM, Martin<[email protected]> wrote:
> [email protected] wrote:
>> A few thoughts:
>>
>> There is no guarantee that any two computation devices (general sense here)
>> will be equally efficient at a particular computation.  The CPU and GPU in
>> a single box may very well have different efficiencies, and should be
>> treated as separate computation devices for credit comparisons.

>> Goal:  The credit granted for all tasks for a single WU needs to be
>> identical, no mater what computation devices it runs on.
>
> Sorry, disagree... What happens for the case where the CPU application
> is highly optimised whereas the GPU application is brazenly wasteful of
> the GPU resource? The GPU does more physical work and gains less credit
> per unit of physical processing work done.

As it should be.  Some applications don't work well on a GPU and may
even be slower on a GPU than a CPU.  Such an application should not be
ported to a GPU in the first place.

> I consider a fairer scheme is that credit is granted for the resource
> actually used.

A resource wasted is different than a resource used.

> If for example, the GPU application (wastefully) for a WU performs twice
> as many calculations as the equivalent CPU application, then the GPU
> processed WU should be awarded twice the credit of the CPU processed WU
> (to reflect the additional resource used/squandered).

Definitely not.  The user should be encouraged (through lower credit)
to use their GPU for a task that is more suited to it.
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