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Commit 42df2714 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Disable waitboosting for fence_wait() 



We want to restrict waitboosting to known process contexts, where we can
track which clients are receiving waitboosts and prevent excessive power
wasting. For fence_wait() we do not have any client tracking and so that
leaves it open to abuse.

v2: Hide the IS_ERR_OR_NULL testing for special clients

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469002875-2335-5-git-send-email-chris@chris-wilson.co.uk
parent 04769652

drivers/gpu/drm/i915/i915_gem_request.c

+4 −3
Original line number Diff line number Diff line
@@ -70,7 +70,7 @@ static signed long i915_fence_wait(struct fence *fence, 


	ret = __i915_wait_request(to_request(fence),

				  interruptible, timeout,

				  NULL);

				  NO_WAITBOOST);

	if (ret == -ETIME)

		return 0;
@@ -642,7 +642,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req, 
	 * forcing the clocks too high for the whole system, we only allow

	 * each client to waitboost once in a busy period.

	 */

	if (INTEL_GEN(req->i915) >= 6)

	if (IS_RPS_CLIENT(rps) && INTEL_GEN(req->i915) >= 6)

		gen6_rps_boost(req->i915, rps, req->emitted_jiffies);



	/* Optimistic spin for the next ~jiffie before touching IRQs */
@@ -713,7 +713,8 @@ int __i915_wait_request(struct drm_i915_gem_request *req, 
			*timeout = 0;

	}



	if (rps && req->fence.seqno == req->engine->last_submitted_seqno) {

	if (IS_RPS_USER(rps) &&

	    req->fence.seqno == req->engine->last_submitted_seqno) {

		/* The GPU is now idle and this client has stalled.

		 * Since no other client has submitted a request in the

		 * meantime, assume that this client is the only one

drivers/gpu/drm/i915/i915_gem_request.h

+3 −0
Original line number Diff line number Diff line
@@ -206,6 +206,9 @@ void __i915_add_request(struct drm_i915_gem_request *req, 
	__i915_add_request(req, NULL, false)



struct intel_rps_client;

#define NO_WAITBOOST ERR_PTR(-1)

#define IS_RPS_CLIENT(p) (!IS_ERR(p))

#define IS_RPS_USER(p) (!IS_ERR_OR_NULL(p))



int __i915_wait_request(struct drm_i915_gem_request *req,

			bool interruptible,