From patchwork Thu Apr 2 18:38:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11471233 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8506814B4 for ; Thu, 2 Apr 2020 18:39:29 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6C49D2064A for ; Thu, 2 Apr 2020 18:39:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C49D2064A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0941C6E141; Thu, 2 Apr 2020 18:39:27 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9D3C86E141 for ; Thu, 2 Apr 2020 18:39:25 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from build.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 20780435-1500050 for multiple; Thu, 02 Apr 2020 19:38:36 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Thu, 2 Apr 2020 19:38:36 +0100 Message-Id: <20200402183836.21508-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915: Keep a per-engine request pools X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Chris Wilson Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Add a tiny per-engine request mempool so that we should always have a request available for powermanagement allocations from tricky contexts. This reserve is expected to be only used for kernel contexts when barriers must be emitted [almost] without fail. This is an alternative to using a comparatively bulky mempool, which requires custom handling for both our reserved allocation requirement and to protect our TYPESAFE_BY_RCU slab cache. Signed-off-by: Chris Wilson Cc: Janusz Krzysztofik Cc: Tvrtko Ursulin --- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 7 +++++ drivers/gpu/drm/i915/gt/intel_engine_types.h | 3 +++ drivers/gpu/drm/i915/i915_request.c | 27 ++++++++++++++++---- drivers/gpu/drm/i915/i915_request.h | 2 ++ 4 files changed, 34 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 843cb6f2f696..5f45c8274203 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -431,7 +431,14 @@ void intel_engines_free(struct intel_gt *gt) struct intel_engine_cs *engine; enum intel_engine_id id; + /* Free the requests! dma-resv keeps fences around for an eternity */ + rcu_barrier(); + for_each_engine(engine, gt, id) { + if (engine->request_pool) + kmem_cache_free(i915_request_slab_cache(), + engine->request_pool); + kfree(engine); gt->engine[id] = NULL; } diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index 80cdde712842..de8e6edcf999 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -308,6 +308,9 @@ struct intel_engine_cs { struct list_head hold; /* ready requests, but on hold */ } active; + /* keep a request in reserve for a [pm] barrier under oom */ + struct i915_request *request_pool; + struct llist_head barrier_tasks; struct intel_context *kernel_context; /* pinned */ diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 3388c5b610c5..22635bbabf06 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -101,6 +101,11 @@ static signed long i915_fence_wait(struct dma_fence *fence, timeout); } +struct kmem_cache *i915_request_slab_cache(void) +{ + return global.slab_requests; +} + static void i915_fence_release(struct dma_fence *fence) { struct i915_request *rq = to_request(fence); @@ -115,6 +120,10 @@ static void i915_fence_release(struct dma_fence *fence) i915_sw_fence_fini(&rq->submit); i915_sw_fence_fini(&rq->semaphore); + /* Keep one request on each engine for reserved use under mempressure */ + if (!cmpxchg(&rq->engine->request_pool, NULL, rq)) + return; + kmem_cache_free(global.slab_requests, rq); } @@ -629,14 +638,22 @@ static void retire_requests(struct intel_timeline *tl) } static noinline struct i915_request * -request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) +request_alloc_slow(struct intel_timeline *tl, + struct i915_request **rsvd, + gfp_t gfp) { struct i915_request *rq; - if (list_empty(&tl->requests)) - goto out; + /* If we cannot wait, dip into our reserves */ + if (!gfpflags_allow_blocking(gfp)) { + rq = xchg(rsvd, NULL); + if (!rq) /* Use the normal failure path for one final WARN */ + goto out; - if (!gfpflags_allow_blocking(gfp)) + return rq; + } + + if (list_empty(&tl->requests)) goto out; /* Move our oldest request to the slab-cache (if not in use!) */ @@ -721,7 +738,7 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp) rq = kmem_cache_alloc(global.slab_requests, gfp | __GFP_RETRY_MAYFAIL | __GFP_NOWARN); if (unlikely(!rq)) { - rq = request_alloc_slow(tl, gfp); + rq = request_alloc_slow(tl, &ce->engine->request_pool, gfp); if (!rq) { ret = -ENOMEM; goto err_unreserve; diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3c552bfea67a..d8ce908e1346 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -300,6 +300,8 @@ static inline bool dma_fence_is_i915(const struct dma_fence *fence) return fence->ops == &i915_fence_ops; } +struct kmem_cache *i915_request_slab_cache(void); + struct i915_request * __must_check __i915_request_create(struct intel_context *ce, gfp_t gfp); struct i915_request * __must_check