From 0340d9fd0f74309f435d5324b885c9ca1967262c Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 4 Aug 2016 16:32:20 +0100 Subject: [PATCH] drm/i915: Remove request retirement before each batch This reimplements the denial-of-service protection against igt from commit 227f782e4667 ("drm/i915: Retire requests before creating a new one") and transfers the stall from before each batch into get_pages(). The issue is that the stall is increasing latency between batches which is detrimental in some cases (especially coupled with execlists) to keeping the GPU well fed. Also we have made the observation that retiring requests can of itself free objects (and requests) and therefore makes a good first step when shrinking. v2: Recycle objects prior to i915_gem_object_get_pages() v3: Remove the reference to the ring from i915_gem_requests_ring() as it operates on an intel_engine_cs. v4: Since commit 9b5f4e5ed6fd ("drm/i915: Retire oldest completed request before allocating next") we no longer need the safeguard to retire requests before get_pages(). We no longer see the huge latencies when hitting the shrinker between allocations. Signed-off-by: Chris Wilson Cc: Daniel Vetter Cc: Joonas Lahtinen Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-4-git-send-email-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_drv.h | 1 - drivers/gpu/drm/i915/i915_gem_execbuffer.c | 2 -- drivers/gpu/drm/i915/i915_gem_request.c | 4 ++-- 3 files changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index fbda38f25c6b..2de3d16f7b80 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -3169,7 +3169,6 @@ struct drm_i915_gem_request * i915_gem_find_active_request(struct intel_engine_cs *engine); void i915_gem_retire_requests(struct drm_i915_private *dev_priv); -void i915_gem_retire_requests_ring(struct intel_engine_cs *engine); static inline u32 i915_reset_counter(struct i915_gpu_error *error) { diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 5e3b5054f72d..0593ea3ba211 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -781,8 +781,6 @@ i915_gem_execbuffer_reserve(struct intel_engine_cs *engine, bool has_fenced_gpu_access = INTEL_GEN(engine->i915) < 4; int retry; - i915_gem_retire_requests_ring(engine); - vm = list_first_entry(vmas, struct i915_vma, exec_list)->vm; INIT_LIST_HEAD(&ordered_vmas); diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c index 6faa84832ade..773b942a3a5f 100644 --- a/drivers/gpu/drm/i915/i915_gem_request.c +++ b/drivers/gpu/drm/i915/i915_gem_request.c @@ -732,7 +732,7 @@ complete: return ret; } -void i915_gem_retire_requests_ring(struct intel_engine_cs *engine) +static void engine_retire_requests(struct intel_engine_cs *engine) { struct drm_i915_gem_request *request, *next; @@ -756,7 +756,7 @@ void i915_gem_retire_requests(struct drm_i915_private *dev_priv) GEM_BUG_ON(!dev_priv->gt.awake); for_each_engine(engine, dev_priv) { - i915_gem_retire_requests_ring(engine); + engine_retire_requests(engine); if (list_empty(&engine->request_list)) dev_priv->gt.active_engines &= ~intel_engine_flag(engine); } -- 2.20.1