From patchwork Wed Jul 1 08:40:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11635701 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 C47AB739 for ; Wed, 1 Jul 2020 08:41:36 +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 AD69C20747 for ; Wed, 1 Jul 2020 08:41:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AD69C20747 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 4BB046E44E; Wed, 1 Jul 2020 08:41:23 +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 D7FDD6E86F for ; Wed, 1 Jul 2020 08:41:15 +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 21671942-1500050 for multiple; Wed, 01 Jul 2020 09:41:00 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Wed, 1 Jul 2020 09:40:34 +0100 Message-Id: <20200701084053.6086-14-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200701084053.6086-1-chris@chris-wilson.co.uk> References: <20200701084053.6086-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 14/33] drm/i915/gt: Convert stats.active to plain unsigned int 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" As context-in/out is now always serialised, we do not have to worry about concurrent enabling/disable of the busy-stats and can reduce the atomic_t active to a plain unsigned int, and the seqlock to a seqcount. Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 8 ++-- drivers/gpu/drm/i915/gt/intel_engine_stats.h | 45 ++++++++++++-------- drivers/gpu/drm/i915/gt/intel_engine_types.h | 4 +- 3 files changed, 34 insertions(+), 23 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index d58e5e251ff3..06a65b280111 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -338,7 +338,7 @@ static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id) engine->schedule = NULL; ewma__engine_latency_init(&engine->latency); - seqlock_init(&engine->stats.lock); + seqcount_init(&engine->stats.lock); ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier); @@ -1617,7 +1617,7 @@ static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine, * add it to the total. */ *now = ktime_get(); - if (atomic_read(&engine->stats.active)) + if (READ_ONCE(engine->stats.active)) total = ktime_add(total, ktime_sub(*now, engine->stats.start)); return total; @@ -1636,9 +1636,9 @@ ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine, ktime_t *now) ktime_t total; do { - seq = read_seqbegin(&engine->stats.lock); + seq = read_seqcount_begin(&engine->stats.lock); total = __intel_engine_get_busy_time(engine, now); - } while (read_seqretry(&engine->stats.lock, seq)); + } while (read_seqcount_retry(&engine->stats.lock, seq)); return total; } diff --git a/drivers/gpu/drm/i915/gt/intel_engine_stats.h b/drivers/gpu/drm/i915/gt/intel_engine_stats.h index 58491eae3482..24fbdd94351a 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_stats.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_stats.h @@ -17,33 +17,44 @@ static inline void intel_engine_context_in(struct intel_engine_cs *engine) { unsigned long flags; - if (atomic_add_unless(&engine->stats.active, 1, 0)) + if (engine->stats.active) { + engine->stats.active++; return; - - write_seqlock_irqsave(&engine->stats.lock, flags); - if (!atomic_add_unless(&engine->stats.active, 1, 0)) { - engine->stats.start = ktime_get(); - atomic_inc(&engine->stats.active); } - write_sequnlock_irqrestore(&engine->stats.lock, flags); + + /* The writer is serialised; but the pmu reader may be from hardirq */ + local_irq_save(flags); + write_seqcount_begin(&engine->stats.lock); + + engine->stats.start = ktime_get(); + engine->stats.active++; + + write_seqcount_end(&engine->stats.lock); + local_irq_restore(flags); + + GEM_BUG_ON(!engine->stats.active); } static inline void intel_engine_context_out(struct intel_engine_cs *engine) { unsigned long flags; - GEM_BUG_ON(!atomic_read(&engine->stats.active)); - - if (atomic_add_unless(&engine->stats.active, -1, 1)) + GEM_BUG_ON(!engine->stats.active); + if (engine->stats.active > 1) { + engine->stats.active--; return; - - write_seqlock_irqsave(&engine->stats.lock, flags); - if (atomic_dec_and_test(&engine->stats.active)) { - engine->stats.total = - ktime_add(engine->stats.total, - ktime_sub(ktime_get(), engine->stats.start)); } - write_sequnlock_irqrestore(&engine->stats.lock, flags); + + local_irq_save(flags); + write_seqcount_begin(&engine->stats.lock); + + engine->stats.active--; + engine->stats.total = + ktime_add(engine->stats.total, + ktime_sub(ktime_get(), engine->stats.start)); + + write_seqcount_end(&engine->stats.lock); + local_irq_restore(flags); } #endif /* __INTEL_ENGINE_STATS_H__ */ diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index b8d8973e6f97..242b6bbd7fe3 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -545,12 +545,12 @@ struct intel_engine_cs { /** * @active: Number of contexts currently scheduled in. */ - atomic_t active; + unsigned int active; /** * @lock: Lock protecting the below fields. */ - seqlock_t lock; + seqcount_t lock; /** * @total: Total time this engine was busy.