On 24-Sep-2011 10:29 PM, Jacob Klein wrote:
> David,
>
> In order to setup the scenario, I removed my GPUGrid and Einstein tasks, then
> let the client figure out what to do. As it went asking projects for more
> work,
> GPUGrid.net got 5 GPU tasks, and then work fetch stopped asking for NVIDIA
> work,
> even though none of those 5 tasks were applicable to the other 2 video cards,
> based on <exclude_gpu> configuration.
>
Jacob:
I fixed this (see notes below).
It was a subtle problem, and using your client state file
as input to the client simulator was key in figuring it out.
-- David
- client: fix a bug reported by Jacob Klein,
where work fetch didn't work right in the presence of
multiple GPUs and <exclude_gpu> config options.
For example: suppose:
- you have 2 GPUs and 2 projects
- Project A is excluded from GPU 1
- you have lots of jobs for project A
Then the client won't try to fetch jobs from project B.
The problem had 2 parts:
a) round-robin simulation wasn't taking GPU exclusions into account.
In the above example, it would think that both GPUs had jobs.
I fixed this by computing the # of GPUs from each project
is excluded, and using this in the RR simulation.
b) Once this was done, I needed to make the client
request GPU jobs from project B rather than project A.
I did this with following policy:
If a project has excluded GPUs of a given type,
and has a runnable job of that type,
don't ask it for more work of that type.
Notes:
- the policy in b) is crude, and it means that work-buffer
preferences are ignored in some cases.
- neither a) nor b) takes into account app-level exclusions.
I could fix both of these with a lot of work,
but I'd rather move to a model in which dissimilar GPUs
are modeled as different resources,
which would remove the need for the <exclude_gpu> mechanism
in the first place.
Other note: I figured out this problem using the client simulator,
based on the client state file that Jacob sent me.
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