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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HK_RANDOM_FROM,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 64D23C54E4A for ; Tue, 12 May 2020 15:17:36 +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 320092054F for ; Tue, 12 May 2020 15:17:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 320092054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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 B71E06E11D; Tue, 12 May 2020 15:17:35 +0000 (UTC) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3BD726E11D for ; Tue, 12 May 2020 15:17:35 +0000 (UTC) IronPort-SDR: FJvEEBvY+1CUQVVztE3FZX98JYkJYXrXd4sCTilYx6SthnsUhvLj/tW8JDSMhCdUjpGinh2YAM 2tFfdIRVvdYA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2020 08:17:34 -0700 IronPort-SDR: z68RCVZzXH1z0txBrATlLS3aREZD+CmaomzXud+Kny/CSeEL7UmDFAMF0CAefhmZu1OAmSVjKz JXIgjyCpKGcQ== X-IronPort-AV: E=Sophos;i="5.73,384,1583222400"; d="scan'208";a="437136397" Received: from dhelmanx-mobl2.ger.corp.intel.com (HELO [10.214.209.74]) ([10.214.209.74]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 May 2020 08:17:33 -0700 To: Chris Wilson , intel-gfx@lists.freedesktop.org References: <20200512132255.20537-1-chris@chris-wilson.co.uk> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc Message-ID: <561ef231-3894-5f9e-d3f2-629537801fb6@linux.intel.com> Date: Tue, 12 May 2020 16:17:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200512132255.20537-1-chris@chris-wilson.co.uk> Content-Language: en-US Subject: Re: [Intel-gfx] [PATCH v2] drm/i915/gt: Transfer old virtual breadcrumbs to irq_worker 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: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 12/05/2020 14:22, Chris Wilson wrote: > The second try at staging the transfer of the breadcrumb. In part one, > we realised we could not simply move to the second engine as we were > only holding the breadcrumb lock on the first. So in commit 6c81e21a4742 > ("drm/i915/gt: Stage the transfer of the virtual breadcrumb"), we > removed it from the first engine and marked up this request to reattach > the signaling on the new engine. However, this failed to take into > account that we only attach the breadcrumb if the new request is added > at the start of the queue, which if we are transferring, it is because > we know there to be a request to be signaled (and hence we would not be > attached). > > In this attempt, we try to transfer the completed requests to the > irq_worker on its rq->engine->breadcrumbs. This preserves the coupling > between the rq and its breadcrumbs, so that > i915_request_cancel_breadcrumb() does not attempt to manipulate the list > under the wrong lock. > > Fixes: 6c81e21a4742 ("drm/i915/gt: Stage the transfer of the virtual breadcrumb") > Signed-off-by: Chris Wilson > Cc: Tvrtko Ursulin > --- > v2: rewrite from scratch with a new idea > --- > drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 33 ++++++++++++++++++++ > drivers/gpu/drm/i915/gt/intel_engine.h | 3 ++ > drivers/gpu/drm/i915/gt/intel_engine_types.h | 2 ++ > drivers/gpu/drm/i915/gt/intel_lrc.c | 26 ++------------- > 4 files changed, 41 insertions(+), 23 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > index cbedba857d43..e09dc162b508 100644 > --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > @@ -155,6 +155,8 @@ static void signal_irq_work(struct irq_work *work) > if (b->irq_armed && list_empty(&b->signalers)) > __intel_breadcrumbs_disarm_irq(b); > > + list_splice_init(&b->signaled_requests, &signal); > + > list_for_each_entry_safe(ce, cn, &b->signalers, signal_link) { > GEM_BUG_ON(list_empty(&ce->signals)); > > @@ -255,6 +257,7 @@ void intel_engine_init_breadcrumbs(struct intel_engine_cs *engine) > > spin_lock_init(&b->irq_lock); > INIT_LIST_HEAD(&b->signalers); > + INIT_LIST_HEAD(&b->signaled_requests); > > init_irq_work(&b->irq_work, signal_irq_work); > } > @@ -274,6 +277,36 @@ void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine) > spin_unlock_irqrestore(&b->irq_lock, flags); > } > > +void intel_engine_transfer_breadcrumbs(struct intel_engine_cs *engine, > + struct intel_context *ce) > +{ > + struct intel_breadcrumbs *b = &engine->breadcrumbs; > + unsigned long flags; > + > + spin_lock_irqsave(&b->irq_lock, flags); > + if (!list_empty(&ce->signals)) { > + struct i915_request *rq, *next; > + > + list_for_each_entry_safe(rq, next, &ce->signals, signal_link) { > + GEM_BUG_ON(rq->engine != engine); > + GEM_BUG_ON(!i915_request_completed(rq)); Do you remember why the breadcrumbs code uses local __request_completed helper? From here vvv > + > + clear_bit(I915_FENCE_FLAG_SIGNAL, &rq->fence.flags); > + if (!__dma_fence_signal(&rq->fence)) > + continue; > + > + i915_request_get(rq); > + list_add_tail(&rq->signal_link, &b->signaled_requests); ^^^ to here looks like a block which could be shared with signal_irq_work. > + } > + > + INIT_LIST_HEAD(&ce->signals); Hm because list_add and not list_move you can't assert all have been unlinked. > + list_del_init(&ce->signal_link); > + > + irq_work_queue(&b->irq_work); > + } > + spin_unlock_irqrestore(&b->irq_lock, flags); > +} > + > void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine) > { > } > diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h > index cb789c8bf06b..45418f887953 100644 > --- a/drivers/gpu/drm/i915/gt/intel_engine.h > +++ b/drivers/gpu/drm/i915/gt/intel_engine.h > @@ -238,6 +238,9 @@ intel_engine_signal_breadcrumbs(struct intel_engine_cs *engine) > void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine); > void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine); > > +void intel_engine_transfer_breadcrumbs(struct intel_engine_cs *engine, > + struct intel_context *ce); > + > void intel_engine_print_breadcrumbs(struct intel_engine_cs *engine, > struct drm_printer *p); > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h > index c113b7805e65..e20b39eefd79 100644 > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h > @@ -377,6 +377,8 @@ struct intel_engine_cs { > spinlock_t irq_lock; > struct list_head signalers; > > + struct list_head signaled_requests; > + > struct irq_work irq_work; /* for use from inside irq_lock */ > > unsigned int irq_enabled; > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c > index 15716e4d6b76..ac32d494b07d 100644 > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c > @@ -1821,30 +1821,10 @@ static bool virtual_matches(const struct virtual_engine *ve, > return true; > } > > -static void virtual_xfer_breadcrumbs(struct virtual_engine *ve, > - struct i915_request *rq) > +static void virtual_xfer_breadcrumbs(struct virtual_engine *ve) > { > - struct intel_engine_cs *old = ve->siblings[0]; > - > /* All unattached (rq->engine == old) must already be completed */ This comments feels a bit out of place now. > - > - spin_lock(&old->breadcrumbs.irq_lock); > - if (!list_empty(&ve->context.signal_link)) { > - list_del_init(&ve->context.signal_link); > - > - /* > - * We cannot acquire the new engine->breadcrumbs.irq_lock > - * (as we are holding a breadcrumbs.irq_lock already), > - * so attach this request to the signaler on submission. > - * The queued irq_work will occur when we finally drop > - * the engine->active.lock after dequeue. > - */ > - set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &rq->fence.flags); > - > - /* Also transfer the pending irq_work for the old breadcrumb. */ > - intel_engine_signal_breadcrumbs(rq->engine); > - } > - spin_unlock(&old->breadcrumbs.irq_lock); > + intel_engine_transfer_breadcrumbs(ve->siblings[0], &ve->context); But isn't ve->siblings[0] the old engine at this point so new target engine would have to be explicitly passed in? > } > > #define for_each_waiter(p__, rq__) \ > @@ -2279,7 +2259,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) > engine); > > if (!list_empty(&ve->context.signals)) > - virtual_xfer_breadcrumbs(ve, rq); > + virtual_xfer_breadcrumbs(ve); > > /* > * Move the bound engine to the top of the list > Regards, Tvrtko _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx