From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?Q2hyaXN0aWFuIEvDtm5pZw==?= Subject: Re: [PATCH 09/17] drm/radeon: use common fence implementation for fences Date: Wed, 23 Jul 2014 09:58:16 +0200 Message-ID: <53CF6B18.5070107@vodafone.de> References: <20140709093124.11354.3774.stgit@patser> <20140709122953.11354.46381.stgit@patser> <53CE2421.5040906@amd.com> <20140722114607.GL15237@phenom.ffwll.local> <20140722115737.GN15237@phenom.ffwll.local> <53CE56ED.4040109@vodafone.de> <20140722132652.GO15237@phenom.ffwll.local> <53CE6AFA.1060807@vodafone.de> <53CE84AA.9030703@amd.com> <53CE8A57.2000803@vodafone.de> <53CF58FB.8070609@canonical.com> <53CF5B9F.1050800@amd.com> <53CF5EFE.6070307@canonical.com> <53CF63C2.7070407@vodafone.de> <53CF6622.6060803@amd.com> <53CF699D.9070902@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <53CF699D.9070902-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: nouveau-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "Nouveau" To: Maarten Lankhorst , =?UTF-8?B?Q2hyaXM=?= =?UTF-8?B?dGlhbiBLw7ZuaWc=?= , Daniel Vetter Cc: Thomas Hellstrom , nouveau , LKML , dri-devel , Ben Skeggs , "Deucher, Alexander" List-Id: nouveau.vger.kernel.org PiBSZWdhcmRsZXNzIG9mIHRoZSBmZW5jZSBpbXBsZW1lbnRhdGlvbiwgd2h5IHdvdWxkIGl0IGJl IGEgZ29vZCBpZGVhIHRvIGRvIGEgZnVsbCBsb2NrdXAgcmVjb3Zlcnkgd2hlbiBzb21lIG90aGVy IGRyaXZlciBpcwo+IGNhbGxpbmcgeW91ciB3YWl0IGZ1bmN0aW9uPyBUaGF0IGRvZXNuJ3Qgc2Vl bSB0byBiZSBhIG5pY2UgdGhpbmcgdG8gZG8sIHNvIEkgdGhpbmsgYSB0aW1lb3V0IGlzIHRoZSBi ZXN0IGVycm9yIHlvdSBjb3VsZCByZXR1cm4gaGVyZSwKPiBvdGhlciBkcml2ZXJzIGhhdmUgdG8g ZGVhbCB3aXRoIHRoYXQgYW55d2F5LgpUaGUgcHJvYmxlbSBpcyB0aGF0IHdlIG5lZWQgdG8gZ3Vh cmFudGVlIHRoYXQgdGhlIGxvY2t1cCB3aWxsIGJlIApyZXNvbHZlZCBldmVudHVhbGx5LgoKSnVz dCBpbWFnaW5lIGFuIGFwcGxpY2F0aW9uIHVzaW5nIHByaW1lIGlzIGxvY2tpbmcgdXAgUmFkZW9u 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dUBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cDovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWls bWFuL2xpc3RpbmZvL25vdXZlYXUK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756524AbaGWH6j (ORCPT ); Wed, 23 Jul 2014 03:58:39 -0400 Received: from pegasos-out.vodafone.de ([80.84.1.38]:55979 "EHLO pegasos-out.vodafone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301AbaGWH6h (ORCPT ); Wed, 23 Jul 2014 03:58:37 -0400 X-Spam-Flag: NO X-Spam-Score: 0.2 Authentication-Results: rohrpostix2.prod.vfnet.de (amavisd-new); dkim=pass header.i=@vodafone.de X-DKIM: OpenDKIM Filter v2.6.8 pegasos-out.vodafone.de 851246A2DE6 X-DKIM: OpenDKIM Filter v2.0.2 smtp-04.vodafone.de 8BEA3E5AB9 Message-ID: <53CF6B18.5070107@vodafone.de> Date: Wed, 23 Jul 2014 09:58:16 +0200 From: =?UTF-8?B?Q2hyaXN0aWFuIEvDtm5pZw==?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Maarten Lankhorst , =?UTF-8?B?Q2hyaXM=?= =?UTF-8?B?dGlhbiBLw7ZuaWc=?= , Daniel Vetter CC: Thomas Hellstrom , nouveau , LKML , dri-devel , Ben Skeggs , "Deucher, Alexander" Subject: Re: [Nouveau] [PATCH 09/17] drm/radeon: use common fence implementation for fences References: <20140709093124.11354.3774.stgit@patser> <20140709122953.11354.46381.stgit@patser> <53CE2421.5040906@amd.com> <20140722114607.GL15237@phenom.ffwll.local> <20140722115737.GN15237@phenom.ffwll.local> <53CE56ED.4040109@vodafone.de> <20140722132652.GO15237@phenom.ffwll.local> <53CE6AFA.1060807@vodafone.de> <53CE84AA.9030703@amd.com> <53CE8A57.2000803@vodafone.de> <53CF58FB.8070609@canonical.com> <53CF5B9F.1050800@amd.com> <53CF5EFE.6070307@canonical.com> <53CF63C2.7070407@vodafone.de> <53CF6622.6060803@amd.com> <53CF699D.9070902@canonical.com> In-Reply-To: <53CF699D.9070902@canonical.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Regardless of the fence implementation, why would it be a good idea to do a full lockup recovery when some other driver is > calling your wait function? That doesn't seem to be a nice thing to do, so I think a timeout is the best error you could return here, > other drivers have to deal with that anyway. The problem is that we need to guarantee that the lockup will be resolved eventually. Just imagine an application using prime is locking up Radeon and because of that gets killed by the user. Nothing else in the system would use the Radeon hardware any more and so radeon gets only called by another driver waiting patiently for radeon to finish rendering which never happens because the whole thing is locked up and we don't get a chance to recover. Christian. Am 23.07.2014 09:51, schrieb Maarten Lankhorst: > op 23-07-14 09:37, Christian König schreef: >> Am 23.07.2014 09:31, schrieb Daniel Vetter: >>> On Wed, Jul 23, 2014 at 9:26 AM, Christian König >>> wrote: >>>> It's not a locking problem I'm talking about here. Radeons lockup handling >>>> kicks in when anything calls into the driver from the outside, if you have a >>>> fence wait function that's called from the outside but doesn't handle >>>> lockups you essentially rely on somebody else calling another radeon >>>> function for the lockup to be resolved. >>> So you don't have a timer in radeon that periodically checks whether >>> progress is still being made? That's the approach we're using in i915, >>> together with some tricks to kick any stuck waiters so that we can >>> reliably step in and grab locks for the reset. >> We tried this approach, but it didn't worked at all. >> >> I already considered trying it again because of the upcoming fence implementation, but reconsidering that when a driver is forced to change it's handling because of the fence implementation that's just another hint that there is something wrong here. > As far as I can tell it wouldn't need to be reworked for the fence implementation currently, only the moment you want to allow callers outside of radeon. :-) > Doing a GPU lockup recovery in the wait function would be messy even right now, you would hit a deadlock in ttm_bo_delayed_delete -> ttm_bo_cleanup_refs_and_unlock. > > Regardless of the fence implementation, why would it be a good idea to do a full lockup recovery when some other driver is > calling your wait function? That doesn't seem to be a nice thing to do, so I think a timeout is the best error you could return here, > other drivers have to deal with that anyway. > > ~Maarten >