From patchwork Thu Dec 17 09:15:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11979321 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF7D0C4361B for ; Thu, 17 Dec 2020 09:15:40 +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 768A32389B for ; Thu, 17 Dec 2020 09:15:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 768A32389B 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 A98F4899C4; Thu, 17 Dec 2020 09:15:37 +0000 (UTC) Received: from fireflyinternet.com (unknown [77.68.26.236]) by gabe.freedesktop.org (Postfix) with ESMTPS id 89580899C4 for ; Thu, 17 Dec 2020 09:15:36 +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 23351916-1500050 for multiple; Thu, 17 Dec 2020 09:15:26 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Thu, 17 Dec 2020 09:15:24 +0000 Message-Id: <20201217091524.10258-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915/gt: Drain the breadcrumbs just once 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" Matthew Brost pointed out that the while-loop on a shared breadcrumb was inherently fraught with danger as it competed with the other users of the breadcrumbs. However, in order to completely drain the re-arming irq worker, the while-loop is a necessity, despite my optimism that we could force cancellation with a couple of irq_work invocations. Given that we can't merely drop the while-loop, use an activity counter on the breadcrumbs to detect when we are parking the breadcrumbs for the last time. Based on a patch by Matthew Brost. Reported-by: Matthew Brost Suggested-by: Matthew Brost Fixes: 9d5612ca165a ("drm/i915/gt: Defer enabling the breadcrumb interrupt to after submission") Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: Matthew Brost Reviewed-by: Matthew Brost --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 10 ++++++---- drivers/gpu/drm/i915/gt/intel_breadcrumbs.h | 13 ++++++++++++- drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h | 6 ++++-- drivers/gpu/drm/i915/gt/intel_engine_pm.c | 1 + 4 files changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 00918300f53f..3c62fd6daa76 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -332,17 +332,19 @@ void intel_breadcrumbs_reset(struct intel_breadcrumbs *b) spin_unlock_irqrestore(&b->irq_lock, flags); } -void intel_breadcrumbs_park(struct intel_breadcrumbs *b) +void __intel_breadcrumbs_park(struct intel_breadcrumbs *b) { - /* Kick the work once more to drain the signalers */ + if (!READ_ONCE(b->irq_armed)) + return; + + /* Kick the work once more to drain the signalers, and disarm the irq */ irq_work_sync(&b->irq_work); - while (unlikely(READ_ONCE(b->irq_armed))) { + while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) { local_irq_disable(); signal_irq_work(&b->irq_work); local_irq_enable(); cond_resched(); } - GEM_BUG_ON(!list_empty(&b->signalers)); } void intel_breadcrumbs_free(struct intel_breadcrumbs *b) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h index ed3d1deabfbd..75cc9cff3ae3 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h @@ -19,7 +19,18 @@ intel_breadcrumbs_create(struct intel_engine_cs *irq_engine); void intel_breadcrumbs_free(struct intel_breadcrumbs *b); void intel_breadcrumbs_reset(struct intel_breadcrumbs *b); -void intel_breadcrumbs_park(struct intel_breadcrumbs *b); +void __intel_breadcrumbs_park(struct intel_breadcrumbs *b); + +static inline void intel_breadcrumbs_unpark(struct intel_breadcrumbs *b) +{ + atomic_inc(&b->active); +} + +static inline void intel_breadcrumbs_park(struct intel_breadcrumbs *b) +{ + if (atomic_dec_and_test(&b->active)) + __intel_breadcrumbs_park(b); +} static inline void intel_engine_signal_breadcrumbs(struct intel_engine_cs *engine) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h b/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h index a74bb3062bd8..d85a6f74fb87 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h @@ -29,8 +29,7 @@ * the overhead of waking that client is much preferred. */ struct intel_breadcrumbs { - /* Not all breadcrumbs are attached to physical HW */ - struct intel_engine_cs *irq_engine; + atomic_t active; spinlock_t signalers_lock; /* protects the list of signalers */ struct list_head signalers; @@ -40,6 +39,9 @@ struct intel_breadcrumbs { struct irq_work irq_work; /* for use from inside irq_lock */ unsigned int irq_enabled; bool irq_armed; + + /* Not all breadcrumbs are attached to physical HW */ + struct intel_engine_cs *irq_engine; }; #endif /* __INTEL_BREADCRUMBS_TYPES__ */ diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c index 499b09cb4acf..d74e748f677a 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c @@ -65,6 +65,7 @@ static int __engine_unpark(struct intel_wakeref *wf) if (engine->unpark) engine->unpark(engine); + intel_breadcrumbs_unpark(engine->breadcrumbs); intel_engine_unpark_heartbeat(engine); return 0; }