gem_wsim: Engine bond command

Engine bonds are an i915 uAPI applicable to load balanced contexts with
engine map. They allow expression rules of engine selection between two
contexts when submissions are also tied with submit fences.

Please refer to the README for a more detailed description.

v2:
 * Use list of symbolic engine names instead of the mask. (Chris)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 50 insertions, 0 deletions

diff --git a/benchmarks/wsim/README b/benchmarks/wsim/README
index 2c085921..c5107326 100644
--- a/benchmarks/wsim/README
+++ b/benchmarks/wsim/README
@@ -7,6 +7,7 @@ B.<uint>
 M.<uint>.<str>[|<str>]...
 P|X.<uint>.<int>
 d|p|s|t|q|a.<int>,...
+b.<uint>.<str>[|<str>].<str>
 f
 
 For duration a range can be given from which a random value will be picked
@@ -26,6 +27,7 @@ Additional workload steps are also supported:
  'f' - Create a sync fence.
  'a' - Advance the previously created sync fence.
  'B' - Turn on context load balancing.
+ 'b' - Set up engine bonds.
  'M' - Set up engine map.
  'P' - Context priority.
  'X' - Context preemption control.
@@ -199,3 +201,51 @@ Example:
   B.1
 
 This enables load balancing for context number one.
+
+Engine bonds
+------------
+
+Engine bonds are extensions on load balanced contexts. They allow expressing
+rules of engine selection between two co-operating contexts tied with submit
+fences. In other words, the rule expression is telling the driver: "If you pick
+this engine for context one, then you have to pick that engine for context two".
+
+Syntax is:
+  b.<context>.<engine_list>.<master_engine>
+
+Engine list is a list of one or more sibling engines separated by a pipe
+character (eg. "VCS1|VCS2").
+
+There can be multiple bonds tied to the same context.
+
+Example:
+
+  M.1.RCS|VECS
+  B.1
+  M.2.VCS1|VCS2
+  B.2
+  b.2.VCS1.RCS
+  b.2.VCS2.VECS
+
+This tells the driver that if it picked RCS for context one, it has to pick VCS1
+for context two. And if it picked VECS for context one, it has to pick VCS1 for
+context two.
+
+If we extend the above example with more workload directives:
+
+  1.DEFAULT.1000.0.0
+  2.DEFAULT.1000.s-1.0
+
+We get to a fully functional example where two batch buffers are submitted in a
+load balanced fashion, telling the driver they should run simultaneously and
+that valid engine pairs are either RCS + VCS1 (for two contexts respectively),
+or VECS + VCS2.
+
+This can also be extended using sync fences to improve chances of the first
+submission not getting on the hardware after the second one. Second block would
+then look like:
+
+  f
+  1.DEFAULT.1000.f-1.0
+  2.DEFAULT.1000.s-1.0
+  a.-3