Re: [Intel-gfx] [PATCH] drm/i915/gem: Allow users to disable waitboost

Wed, 27 Sep 2023 12:35:06 -0700 


On 9/21/2023 3:41 AM, Tvrtko Ursulin wrote:


On 20/09/2023 22:56, Vinay Belgaumkar wrote:

Provide a bit to disable waitboost while waiting on a gem object.
Waitboost results in increased power consumption by requesting RP0
while waiting for the request to complete. Add a bit in the gem_wait()
IOCTL where this can be disabled.

This is related to the libva API change here -

Link: 
https://github.com/XinfengZhang/libva/commit/3d90d18c67609a73121bb71b20ee4776b54b61a7


This link does not appear to lead to userspace code using this uapi?

We have asked Carl (cc'd) to post a patch for the same.




Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaum...@intel.com>
---
  drivers/gpu/drm/i915/gem/i915_gem_wait.c | 9 ++++++---
  drivers/gpu/drm/i915/i915_request.c      | 3 ++-
  drivers/gpu/drm/i915/i915_request.h      | 1 +
  include/uapi/drm/i915_drm.h              | 1 +
  4 files changed, 10 insertions(+), 4 deletions(-)


diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c 
b/drivers/gpu/drm/i915/gem/i915_gem_wait.c

index d4b918fb11ce..955885ec859d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c

@@ -72,7 +72,8 @@ i915_gem_object_wait_reservation(struct dma_resv 
*resv,

      struct dma_fence *fence;
      long ret = timeout ?: 1;
  -    i915_gem_object_boost(resv, flags);
+    if (!(flags & I915_WAITBOOST_DISABLE))
+        i915_gem_object_boost(resv, flags);
        dma_resv_iter_begin(&cursor, resv,
                  dma_resv_usage_rw(flags & I915_WAIT_ALL));

@@ -236,7 +237,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void 
*data, struct drm_file *file)

      ktime_t start;
      long ret;
  -    if (args->flags != 0)
+    if (args->flags != 0 || args->flags != I915_GEM_WAITBOOST_DISABLE)
          return -EINVAL;
        obj = i915_gem_object_lookup(file, args->bo_handle);

@@ -248,7 +249,9 @@ i915_gem_wait_ioctl(struct drm_device *dev, void 
*data, struct drm_file *file)

      ret = i915_gem_object_wait(obj,
                     I915_WAIT_INTERRUPTIBLE |
                     I915_WAIT_PRIORITY |
-                   I915_WAIT_ALL,
+                   I915_WAIT_ALL |
+                   (args->flags & I915_GEM_WAITBOOST_DISABLE ?
+                    I915_WAITBOOST_DISABLE : 0),
                     to_wait_timeout(args->timeout_ns));
        if (args->timeout_ns > 0) {

diff --git a/drivers/gpu/drm/i915/i915_request.c 
b/drivers/gpu/drm/i915/i915_request.c

index f59081066a19..2957409b4b2a 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c

@@ -2044,7 +2044,8 @@ long i915_request_wait_timeout(struct 
i915_request *rq,

       * but at a cost of spending more power processing the workload
       * (bad for battery).
       */
-    if (flags & I915_WAIT_PRIORITY && !i915_request_started(rq))

+    if (!(flags & I915_WAITBOOST_DISABLE) && (flags & 
I915_WAIT_PRIORITY) &&

+        !i915_request_started(rq))
          intel_rps_boost(rq);
        wait.tsk = current;

diff --git a/drivers/gpu/drm/i915/i915_request.h 
b/drivers/gpu/drm/i915/i915_request.h

index 0ac55b2e4223..3cc00e8254dc 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -445,6 +445,7 @@ long i915_request_wait(struct i915_request *rq,
  #define I915_WAIT_INTERRUPTIBLE    BIT(0)

  #define I915_WAIT_PRIORITY    BIT(1) /* small priority bump for the 
request */
  #define I915_WAIT_ALL        BIT(2) /* used by 
i915_gem_object_wait() */
+#define I915_WAITBOOST_DISABLE    BIT(3) /* used by 
i915_gem_object_wait() */

    void i915_request_show(struct drm_printer *m,
                 const struct i915_request *rq,
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 7000e5910a1d..4adee70e39cf 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1928,6 +1928,7 @@ struct drm_i915_gem_wait {
      /** Handle of BO we shall wait on */
      __u32 bo_handle;
      __u32 flags;
+#define I915_GEM_WAITBOOST_DISABLE      (1u<<0)



Probably would be good to avoid mentioning waitboost in the uapi since 
so far it wasn't an explicit feature/contract. Something like 
I915_GEM_WAIT_BACKGROUND_PRIORITY? Low priority?

sure.



I also wonder if there could be a possible angle to help Rob (+cc) 
upstream the syncobj/fence deadline code if our media driver might 
make use of that somehow.



Like if either we could wire up the deadline into GEM_WAIT (in a 
backward compatible manner), or if media could use sync fd wait 
instead. Assuming they have an out fence already, which may not be true.



Makes sense. We could add a SET_DEADLINE flag or something similar and 
pass in the deadline when appropriate.


Thanks,

Vinay.



Regards,

Tvrtko


      /** Number of nanoseconds to wait, Returns time remaining. */
      __s64 timeout_ns;
  };






















					Reply via email to