From mboxrd@z Thu Jan 1 00:00:00 1970 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=-5.9 required=3.0 tests=DATE_IN_PAST_12_24, DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 1C916C2BA19 for ; Mon, 13 Apr 2020 07:34:24 +0000 (UTC) Received: from vger.kernel.org (unknown [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0B8220735 for ; Mon, 13 Apr 2020 07:34:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ji8uZGHB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0B8220735 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=stable-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727612AbgDMHeX (ORCPT ); Mon, 13 Apr 2020 03:34:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.18]:33558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727480AbgDMHeW (ORCPT ); Mon, 13 Apr 2020 03:34:22 -0400 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 072FBC008651 for ; Mon, 13 Apr 2020 00:34:22 -0700 (PDT) Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C1FB20735; Mon, 13 Apr 2020 07:34:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586763261; bh=w1Ylgew/C4PnWfGYGTwdlgKSuyok4jA8oTfJgBPAoms=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ji8uZGHBO/23NP4IHJiAsdNz1eZlO5FIhttS1eC2nB15m1sqtdjsIHgt8oeMTg06n 7piVQRaEtr//4mabjnTwWS/jcM1ty6fF0fqKcfj3UCBwfwVel23xst6eg4EkuaElzB Y6KINm1/7SDGww7cEpQ2fwedkqAlgvGMkjWL2Gxs= Date: Sun, 12 Apr 2020 09:56:07 +0200 From: Greg KH To: Sultan Alsawaf Cc: stable@vger.kernel.org Subject: Re: [PATCH v2] drm/i915/gt: Schedule request retirement when timeline idles Message-ID: <20200412075607.GA2709076@kroah.com> References: <20200407202856.GA2026@sultan-box.localdomain> <20200407204345.3498-1-sultan@kerneltoast.com> <20200412074851.GA2703@sultan-book.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200412074851.GA2703@sultan-book.localdomain> Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sun, Apr 12, 2020 at 12:48:51AM -0700, Sultan Alsawaf wrote: > On Tue, Apr 07, 2020 at 01:43:45PM -0700, Sultan Alsawaf wrote: > > From: Chris Wilson > > > > The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX > > corruption WA") is that it disables RC6 while Skylake (and friends) is > > active, and we do not consider the GPU idle until all outstanding > > requests have been retired and the engine switched over to the kernel > > context. If userspace is idle, this task falls onto our background idle > > worker, which only runs roughly once a second, meaning that userspace has > > to have been idle for a couple of seconds before we enable RC6 again. > > Naturally, this causes us to consume considerably more energy than > > before as powersaving is effectively disabled while a display server > > (here's looking at you Xorg) is running. > > > > As execlists will get a completion event as each context is completed, > > we can use this interrupt to queue a retire worker bound to this engine > > to cleanup idle timelines. We will then immediately notice the idle > > engine (without userspace intervention or the aid of the background > > retire worker) and start parking the GPU. Thus during light workloads, > > we will do much more work to idle the GPU faster... Hopefully with > > commensurate power saving! > > > > v2: Watch context completions and only look at those local to the engine > > when retiring to reduce the amount of excess work we perform. > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 > > References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") > > References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") > > Signed-off-by: Chris Wilson > > Cc: Tvrtko Ursulin > > Reviewed-by: Tvrtko Ursulin > > Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris@chris-wilson.co.uk > > (cherry picked from commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51) > > > > For the backport to 5.4, struct_mutex needs to be held while retiring so > > that retirement doesn't race with vma destruction. > > Signed-off-by: Sultan Alsawaf > > --- > > drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + > > drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ > > drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ > > drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + > > .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + > > drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ > > drivers/gpu/drm/i915/i915_request.h | 4 + > > 7 files changed, 101 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c > > index 4ce8626b140e..f732a2177cd0 100644 > > --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c > > @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) > > intel_engine_init_hangcheck(engine); > > intel_engine_init_cmd_parser(engine); > > intel_engine_init__pm(engine); > > + intel_engine_init_retire(engine); > > > > intel_engine_pool_init(&engine->pool); > > > > @@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine) > > > > cleanup_status_page(engine); > > > > + intel_engine_fini_retire(engine); > > intel_engine_pool_fini(&engine->pool); > > intel_engine_fini_breadcrumbs(engine); > > intel_engine_cleanup_cmd_parser(engine); > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h > > index c77c9518c58b..1eb7189f88e1 100644 > > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h > > @@ -471,6 +471,14 @@ struct intel_engine_cs { > > > > struct intel_engine_execlists execlists; > > > > + /* > > + * Keep track of completed timelines on this engine for early > > + * retirement with the goal of quickly enabling powersaving as > > + * soon as the engine is idle. > > + */ > > + struct intel_timeline *retire; > > + struct work_struct retire_work; > > + > > /* status_notifier: list of callbacks for context-switch changes */ > > struct atomic_notifier_head context_status_notifier; > > > > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c > > index 66f6d1a897f2..a1538c8f7922 100644 > > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c > > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c > > @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, > > { > > struct intel_context * const ce = rq->hw_context; > > > > + /* > > + * If we have just completed this context, the engine may now be > > + * idle and we want to re-enter powersaving. > > + */ > > + if (list_is_last(&rq->link, &ce->timeline->requests) && > > + i915_request_completed(rq)) > > + intel_engine_add_retire(engine, ce->timeline); > > + > > intel_engine_context_out(engine); > > execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); > > intel_gt_pm_put(engine->gt); > > diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c > > index 9cb01d9828f1..63515e3caaf2 100644 > > --- a/drivers/gpu/drm/i915/gt/intel_timeline.c > > +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c > > @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) > > { > > GEM_BUG_ON(atomic_read(&timeline->pin_count)); > > GEM_BUG_ON(!list_empty(&timeline->requests)); > > + GEM_BUG_ON(timeline->retire); > > > > if (timeline->hwsp_cacheline) > > cacheline_free(timeline->hwsp_cacheline); > > diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h > > index 2b1baf2fcc8e..adf2d14ef647 100644 > > --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h > > +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h > > @@ -65,6 +65,9 @@ struct intel_timeline { > > */ > > struct i915_active_request last_request; > > > > + /** A chain of completed timelines ready for early retirement. */ > > + struct intel_timeline *retire; > > + > > /** > > * We track the most recent seqno that we wait on in every context so > > * that we only have to emit a new await and dependency on a more > > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c > > index 0d39038898d4..35457fda350c 100644 > > --- a/drivers/gpu/drm/i915/i915_request.c > > +++ b/drivers/gpu/drm/i915/i915_request.c > > @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) > > break; > > } > > > > +static void engine_retire(struct work_struct *work) > > +{ > > + struct intel_engine_cs *engine = > > + container_of(work, typeof(*engine), retire_work); > > + struct intel_timeline *tl = xchg(&engine->retire, NULL); > > + > > + do { > > + struct intel_timeline *next = xchg(&tl->retire, NULL); > > + > > + /* > > + * Our goal here is to retire _idle_ timelines as soon as > > + * possible (as they are idle, we do not expect userspace > > + * to be cleaning up anytime soon). > > + * > > + * If the timeline is currently locked, either it is being > > + * retired elsewhere or about to be! > > + */ > > + mutex_lock(&engine->i915->drm.struct_mutex); > > + if (mutex_trylock(&tl->mutex)) { > > + retire_requests(tl); > > + mutex_unlock(&tl->mutex); > > + } > > + mutex_unlock(&engine->i915->drm.struct_mutex); > > + intel_timeline_put(tl); > > + > > + GEM_BUG_ON(!next); > > + tl = ptr_mask_bits(next, 1); > > + } while (tl); > > +} > > + > > +static bool add_retire(struct intel_engine_cs *engine, > > + struct intel_timeline *tl) > > +{ > > + struct intel_timeline *first; > > + > > + /* > > + * We open-code a llist here to include the additional tag [BIT(0)] > > + * so that we know when the timeline is already on a > > + * retirement queue: either this engine or another. > > + * > > + * However, we rely on that a timeline can only be active on a single > > + * engine at any one time and that add_retire() is called before the > > + * engine releases the timeline and transferred to another to retire. > > + */ > > + > > + if (READ_ONCE(tl->retire)) /* already queued */ > > + return false; > > + > > + intel_timeline_get(tl); > > + first = READ_ONCE(engine->retire); > > + do > > + tl->retire = ptr_pack_bits(first, 1, 1); > > + while (!try_cmpxchg(&engine->retire, &first, tl)); > > + > > + return !first; > > +} > > + > > +void intel_engine_add_retire(struct intel_engine_cs *engine, > > + struct intel_timeline *tl) > > +{ > > + if (add_retire(engine, tl)) > > + schedule_work(&engine->retire_work); > > +} > > + > > +void intel_engine_init_retire(struct intel_engine_cs *engine) > > +{ > > + INIT_WORK(&engine->retire_work, engine_retire); > > +} > > + > > +void intel_engine_fini_retire(struct intel_engine_cs *engine) > > +{ > > + flush_work(&engine->retire_work); > > + GEM_BUG_ON(engine->retire); > > +} > > + > > static noinline struct i915_request * > > request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) > > { > > diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h > > index 3a3e7bbf19ff..40caa2f3f4a4 100644 > > --- a/drivers/gpu/drm/i915/i915_request.h > > +++ b/drivers/gpu/drm/i915/i915_request.h > > @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) > > } > > > > bool i915_retire_requests(struct drm_i915_private *i915); > > +void intel_engine_init_retire(struct intel_engine_cs *engine); > > +void intel_engine_add_retire(struct intel_engine_cs *engine, > > + struct intel_timeline *tl); > > +void intel_engine_fini_retire(struct intel_engine_cs *engine); > > > > #endif /* I915_REQUEST_H */ > > -- > > 2.26.0 > > > > Hi Greg, > > Could you queue this one up as well? What is the git commit id of this in Linus's tree?