From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: Remove unecessary per execlist queue item pm reference Date: Mon, 20 Oct 2014 18:30:58 +0200 Message-ID: <20141020163058.GW26941@phenom.ffwll.local> References: <1413801096-17706-1-git-send-email-nicholas.hoath@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com [209.85.212.169]) by gabe.freedesktop.org (Postfix) with ESMTP id 7C2C16E0D8 for ; Mon, 20 Oct 2014 09:30:50 -0700 (PDT) Received: by mail-wi0-f169.google.com with SMTP id h11so9567469wiw.0 for ; Mon, 20 Oct 2014 09:30:49 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1413801096-17706-1-git-send-email-nicholas.hoath@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Nick Hoath Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Mon, Oct 20, 2014 at 11:31:36AM +0100, Nick Hoath wrote: > The execlist code was holding a pm reference for the lifetime of an > execlist queue item. Having this pm reference is required when getting > force wakes during execlists_elsp_write. As this happens inside an interrupt > handler and retrieving the reference can sleep, it can't be done more fine > grained. However, the matching execbuffer already holds a pm reference which > covers this timeframe. That's not entirely accurate. We keep the gpu out of runtime pm as long as it's busy, which is done by the intel_mark_busy/idle functions. The requests themselves don't actually hold a runtime pm reference. Can you please update commit message and comments? Also, I don't think this works without also reworking the way we retire execlist items since atm they're retired in a complete separate work item. So you can't actually rely on the overal gpu business runtime pm. I think we need to assemeble all the different pieces of the request/execlist puzzle into one patch series. Looking at each individual piece doesn't make a lot of sense to me. Thanks, Daniel > > Issue: VIZ-4274 > Signed-off-by: Nick Hoath > --- > drivers/gpu/drm/i915/intel_lrc.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c > index 1be836a..dc096de 100644 > --- a/drivers/gpu/drm/i915/intel_lrc.c > +++ b/drivers/gpu/drm/i915/intel_lrc.c > @@ -297,7 +297,7 @@ static void execlists_elsp_write(struct intel_engine_cs *ring, > * > * The other problem is that we can't just call gen6_gt_force_wake_get() > * because that function calls intel_runtime_pm_get(), which might sleep. > - * Instead, we do the runtime_pm_get/put when creating/destroying requests. > + * Instead, we rely on the requests pm get/put. > */ > spin_lock_irqsave(&dev_priv->uncore.lock, flags); > if (IS_CHERRYVIEW(dev_priv->dev)) { > @@ -519,8 +519,6 @@ static void execlists_free_request_task(struct work_struct *work) > struct drm_device *dev = req->ring->dev; > struct drm_i915_private *dev_priv = dev->dev_private; > > - intel_runtime_pm_put(dev_priv); > - > mutex_lock(&dev->struct_mutex); > i915_gem_context_unreference(req->ctx); > mutex_unlock(&dev->struct_mutex); > @@ -546,8 +544,6 @@ static int execlists_context_queue(struct intel_engine_cs *ring, > req->tail = tail; > INIT_WORK(&req->work, execlists_free_request_task); > > - intel_runtime_pm_get(dev_priv); > - > spin_lock_irqsave(&ring->execlist_lock, flags); > > list_for_each_entry(cursor, &ring->execlist_queue, execlist_link) > -- > 2.1.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch