The joy of our hardware; don't let two threads attempt to read the same
register at the same time.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Allow the producers to be set with maximum RT priority to verify that
the waiters are not exhibiting priorty-inversion.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Try a different pattern to cascade the cancellation from producers to
their consumers in order to avoid one potential deadlock.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Do the workload before the nop, so that if combining both, there is a
better chance for the spurious interrupts. Emit just one workload batch
(use the nops to generate spurious interrupts) and apply the factor to
the number of copies to make inside the workload - the intention is that
this gives sufficient time for all producers to run concurrently.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Split the distinct phases (generate interrupts, busywork, measure
latency) into separate batches for finer control.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Knowing how long it takes to execute the workload (and how that scales)
is interesting to put the latency figures into perspective.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Late last night I forgot I had only added the llc CPU mmaping and not
the !llc GTT mapping for byt/bsw.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
The goal is measure how long it takes for clients waiting on results to
wakeup after a buffer completes, and in doing so ensure scalibilty of
the kernel to large number of clients.
We spawn a number of producers. Each producer submits a busyload to the
system and records in the GPU the BCS timestamp of when the batch
completes. Then each producer spawns a number of waiters, who wait upon
the batch completion and measure the current BCS timestamp register and
compare against the recorded value.
By varying the number of producers and consumers, we can study different
aspects of the design, in particular how many wakeups the kernel does
for each interrupt (end of batch). The more wakeups on each batch, the
longer it takes for any one client to finish.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
