From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maarten Lankhorst Subject: Re: [PATCH 17/19] drm/radeon: use rcu waits in some ioctls Date: Mon, 04 Aug 2014 10:56:42 +0200 Message-ID: <53DF4ACA.7060402@canonical.com> 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> <53DF4761.7040109@daenzer.net> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by gabe.freedesktop.org (Postfix) with ESMTP id C57EB89D8E for ; Mon, 4 Aug 2014 01:56:43 -0700 (PDT) In-Reply-To: <53DF4761.7040109@daenzer.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: =?windows-1252?Q?Michel_D=E4nzer?= Cc: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org op 04-08-14 10:42, Michel D=E4nzer schreef: > 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_devi= ce *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, = true, 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.ht= ml >>>>> 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. Because in the worst case you didn't wait on the fence that started the evi= ction, but one before it. ;-) ~Maarten