From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?windows-1252?Q?Michel_D=E4nzer?= Subject: Re: [PATCH 17/19] drm/radeon: use rcu waits in some ioctls Date: Mon, 04 Aug 2014 17:42:09 +0900 Message-ID: <53DF4761.7040109@daenzer.net> References: <20140731153245.15061.63023.stgit@patser> <20140731153432.15061.49403.stgit@patser> <53DB4F5D.8000101@daenzer.net> <53DB680F.8000402@canonical.com> <53DBA076.2090503@daenzer.net> <53DBC96B.4010905@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mail.gna.ch (darkcity.gna.ch [195.226.6.51]) by gabe.freedesktop.org (Postfix) with ESMTP id C5DA26E0F9 for ; Mon, 4 Aug 2014 01:42:14 -0700 (PDT) In-Reply-To: <53DBC96B.4010905@canonical.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Maarten Lankhorst Cc: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org On 02.08.2014 02:07, Maarten Lankhorst wrote: > On 01-08-14 16:13, Michel D=E4nzer wrote: >> On 01.08.2014 19:12, Maarten Lankhorst wrote: >>> On 01-08-14 10:27, Michel D=E4nzer wrote: >>>> On 01.08.2014 00:34, Maarten Lankhorst wrote: >>>>> >>>>> @@ -357,14 +360,20 @@ int radeon_gem_wait_idle_ioctl(struct drm_devic= e *dev, void *data, >>>>> struct drm_radeon_gem_wait_idle *args =3D data; >>>>> struct drm_gem_object *gobj; >>>>> struct radeon_bo *robj; >>>>> - int r; >>>>> + int r =3D 0; >>>>> + long ret; >>>>> = >>>>> gobj =3D drm_gem_object_lookup(dev, filp, args->handle); >>>>> if (gobj =3D=3D NULL) { >>>>> return -ENOENT; >>>>> } >>>>> robj =3D gem_to_radeon_bo(gobj); >>>>> - r =3D radeon_bo_wait(robj, NULL, false); >>>>> + ret =3D reservation_object_wait_timeout_rcu(robj->tbo.resv, true, t= rue, 30 * HZ); >>>>> + if (ret =3D=3D 0) >>>>> + r =3D -EBUSY; >>>>> + else if (ret < 0) >>>>> + r =3D ret; >>>>> + >>>>> /* callback hw specific functions if any */ >>>>> if (rdev->asic->ioctl_wait_idle) >>>>> robj->rdev->asic->ioctl_wait_idle(rdev, robj); >>>> >>>> Heads up, this conflicts with >>>> http://lists.freedesktop.org/archives/dri-devel/2014-August/065255.html >>>> which passes a non-NULL second argument to radeon_bo_wait() to get the >>>> BO's current domain. >>> Ok, I will fix it up and resend it later. >>> >>> Does it matter if I grab the current domain without grabbing the lock >>> here? Because it doesn't matter if it sees the old or new domain, it >>> could have been changed after returning too. >> >> It should be the domain where the BO is located when the fence we are >> waiting for here signals. > Could we compare domain before and after the rcu wait, and retry > waiting if they're different, and the new one is VRAM? (eg eviction > happened) That should prevent needing to lock the bo. Eviction normally only happens from VRAM, not to VRAM. :) So if you know whether the domain is VRAM or not after the wait, you can just proceed accordingly, I don't see why you'd need to wait again. -- = Earthling Michel D=E4nzer | http://www.amd.com Libre software enthusiast | Mesa and X developer