[PATCH 0/2] optimization on shadow ctx population and updating

[Yan Zhao]

patch 1 removes repeatedly calling to kmap()/kunmap() for accessing shadow
ctx pages. Instead, it accesses the pages through its base virtual
address.

patch 2 combines guest ctx pages access if the guest context pages are
found to be contiguous in IOVA.

with the two patches,
average cycles for populate_shadow_context() and update_guest_context()
are reduced by ~10000-20000 cycles, depending on the average number of
consecutive pages in each read/write.

(1) comparison of cycles of
populate_shadow_context() + update_guest_context() when executing
different benchmarks
 -------------------------------------------------------------
|       cycles      | glmark2     | lightsmark  | openarena   |
|-------------------------------------------------------------|
| before this patch | 65968       | 97852       | 61373       |
|  after this patch | 56017 (85%) | 73862 (75%) | 47463 (77%) |
 -------------------------------------------------------------

(2) average count of pages read/written a time in
populate_shadow_context() and update_guest_context()
for each benchmark

 -----------------------------------------------------------
|     page cnt      | glmark2     | lightsmark  | openarena |
|-----------------------------------------------------------|
| before this patch |    1        |      1      |    1      |
|  after this patch |    5.25     |     19.99   |   20      |
 ------------------------------------------------------------

(3) comparison of benchmarks scores
 ---------------------------------------------------------------------
|      score        | glmark2       | lightsmark     | openarena      |
|---------------------------------------------------------------------|
| before this patch | 1244          | 222.18         | 114.4          |
|  after this patch | 1248 (100.3%) | 225.8 (101.6%) | 115.0 (100.9%) |
 ---------------------------------------------------------------------
 
Yan Zhao (2):
  drm/i915/gvt: access shadow ctx via its virtual address directly
  drm/i915/gvt: combine access to consecutive guest context pages

 drivers/gpu/drm/i915/gvt/scheduler.c | 93 +++++++++++++++++++---------
 1 file changed, 65 insertions(+), 28 deletions(-)

-- 
2.17.1