benchmark: Measure of latency of producers -> consumers, gem_latency

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>

1 files changed, 1 insertions, 0 deletions

diff --git a/benchmarks/Makefile.sources b/benchmarks/Makefile.sources
index fd811955..55c8fde3 100644
--- a/benchmarks/Makefile.sources
+++ b/benchmarks/Makefile.sources
@@ -11,6 +11,7 @@ benchmarks_PROGRAMS =			\
 	gem_exec_nop			\
 	gem_exec_reloc			\
 	gem_exec_trace			\
+	gem_latency			\
 	gem_mmap			\
 	gem_prw				\
 	gem_set_domain			\