Re: [igt-dev] [Intel-gfx] [PATCH i-g-t] benchmarks/wsim: Simulate and interpret .wsim

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 11/05/2018 10:04, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-05-11 09:31:52)
>>
>> On 11/05/2018 08:11, Chris Wilson wrote:
>>> A little tool I've been meaning to write for a while... Convert the
>>> .wsim into their dag and find the longest chains and evaluate them on an
>>> simulated machine.
>>
>> Very cool!
>>
>> But I think you need to handle the 's' command which appears in the
>> interesting workloads. Maybe you could just fake it as a zero duration
>> batch with a data dependency.
> 
> Barriers were even more trivial than that. :)
>   
>> Fence related commands would also be useful but more difficult I guess.
>> As would throttling.
> 
> I haven't groked your fence command lines so skipped them. Fortunately,
> syncs appears to be the only one missed from the "interesting" set of
> wsim.

Fences are created with 'f' and then batches can reference them from the 
dependency list the same as with data dependencies. When created they 
are unsignaled and then 'a' advances the fence addresses relatively to 
the 'a' command. For instance 'a.-2' means "signal ready the fence 
created two steps above".

>> Delays could maybe be faked as batches as well by adding input
>> dependency to everything preceding it.
> 
> It would definitely want to be a task with say .engine = -1. It implies
> a full barrier as well? Not limited to waiting for an earlier step?

There is 'd' which is a normal/dumb fixed delay, and then 'p' which is 
relative to start of the loop, meaning "wait how much is needed so that 
time from start of loop to this step is x".

Regards,

Tvrtko
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