From patchwork Tue Aug 7 07:29:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10558287 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4FE78157D for ; Tue, 7 Aug 2018 07:29:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2EED529736 for ; Tue, 7 Aug 2018 07:29:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 22B3729783; Tue, 7 Aug 2018 07:29:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6912029736 for ; Tue, 7 Aug 2018 07:29:31 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A3B6B6E1C8; Tue, 7 Aug 2018 07:29:30 +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 41D4B6E1C8 for ; Tue, 7 Aug 2018 07:29:29 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 12671717-1500050 for multiple; Tue, 07 Aug 2018 08:29:15 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 7 Aug 2018 08:29:14 +0100 Message-Id: <20180807072914.30047-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180806083017.32215-4-chris@chris-wilson.co.uk> References: <20180806083017.32215-4-chris@chris-wilson.co.uk> Subject: [Intel-gfx] [PATCH v2] drm/i915: Priority boost for new clients X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Taken from an idea used for FQ_CODEL, we give the first request of a new request flows a small priority boost. These flows are likely to correspond with short, interactive tasks and so be more latency sensitive than the longer free running queues. As soon as the client has more than one request in the queue, further requests are not boosted and it settles down into ordinary steady state behaviour. Such small kicks dramatically help combat the starvation issue, by allowing each client the opportunity to run even when the system is under heavy throughput load (within the constraints of the user selected priority). v2: Mark the preempted request as the start of a new flow, to prevent a single client being continually gazumped by its peers. Testcase: igt/benchmarks/rrul Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: Joonas Lahtinen --- drivers/gpu/drm/i915/i915_request.c | 16 ++++++++++++++-- drivers/gpu/drm/i915/i915_scheduler.h | 4 +++- drivers/gpu/drm/i915/intel_lrc.c | 23 ++++++++++++++++++----- 3 files changed, 35 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index fdcd48651973..334a56daefad 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1125,8 +1125,20 @@ void i915_request_add(struct i915_request *request) */ local_bh_disable(); rcu_read_lock(); /* RCU serialisation for set-wedged protection */ - if (engine->schedule) - engine->schedule(request, &request->gem_context->sched); + if (engine->schedule) { + struct i915_sched_attr attr = request->gem_context->sched; + + /* + * Boost priorities to new clients (new request flows). + * + * Allow interactive/synchronous clients to jump ahead of + * the bulk clients. (FQ_CODEL) + */ + if (!prev || i915_request_completed(prev)) + attr.priority |= I915_PRIORITY_NEWCLIENT; + + engine->schedule(request, &attr); + } rcu_read_unlock(); i915_sw_fence_commit(&request->submit); local_bh_enable(); /* Kick the execlists tasklet if just scheduled */ diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h index 7edfad0abfd7..e9fb6c1d5e42 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.h +++ b/drivers/gpu/drm/i915/i915_scheduler.h @@ -19,12 +19,14 @@ enum { I915_PRIORITY_INVALID = INT_MIN }; -#define I915_USER_PRIORITY_SHIFT 0 +#define I915_USER_PRIORITY_SHIFT 1 #define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT) #define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT) #define I915_PRIORITY_MASK (-I915_PRIORITY_COUNT) +#define I915_PRIORITY_NEWCLIENT BIT(0) + struct i915_sched_attr { /** * @priority: execution and service priority diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 1558214eb502..6dec59872282 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -363,9 +363,9 @@ static void unwind_wa_tail(struct i915_request *rq) static void __unwind_incomplete_requests(struct intel_engine_cs *engine) { - struct i915_request *rq, *rn; + struct i915_request *rq, *rn, *active = NULL; struct list_head *uninitialized_var(pl); - int last_prio = I915_PRIORITY_INVALID; + int prio = I915_PRIORITY_INVALID; lockdep_assert_held(&engine->timeline.lock); @@ -379,12 +379,25 @@ static void __unwind_incomplete_requests(struct intel_engine_cs *engine) unwind_wa_tail(rq); GEM_BUG_ON(rq_prio(rq) == I915_PRIORITY_INVALID); - if (rq_prio(rq) != last_prio) { - last_prio = rq_prio(rq); - pl = lookup_priolist(engine, last_prio); + if (rq_prio(rq) != prio) { + prio = rq_prio(rq); + pl = lookup_priolist(engine, prio); } list_add(&rq->sched.link, pl); + + active = rq; + } + + /* + * The active request is now effectively the start of a new client + * stream, so give it the equivalent small priority bump to prevent + * it being gazumped a second time by another peer. + */ + if (!(prio & I915_PRIORITY_NEWCLIENT)) { + list_move_tail(&active->sched.link, + lookup_priolist(engine, + prio | I915_PRIORITY_NEWCLIENT)); } }