From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756053AbaGVPmT (ORCPT ); Tue, 22 Jul 2014 11:42:19 -0400 Received: from mail-qa0-f50.google.com ([209.85.216.50]:53549 "EHLO mail-qa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391AbaGVPmS convert rfc822-to-8bit (ORCPT ); Tue, 22 Jul 2014 11:42:18 -0400 MIME-Version: 1.0 In-Reply-To: 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> <53CE6FB0.90500@canonical.com> <53CE7410.3090603@amd.com> <53CE74B5.3000201@canonical.com> <53CE77B4.6020801@amd.com> Date: Tue, 22 Jul 2014 11:42:17 -0400 Message-ID: Subject: Re: [PATCH 09/17] drm/radeon: use common fence implementation for fences From: Alex Deucher To: Daniel Vetter Cc: =?UTF-8?Q?Christian_K=C3=B6nig?= , Thomas Hellstrom , nouveau , LKML , dri-devel , "Deucher, Alexander" , Ben Skeggs Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 22, 2014 at 11:19 AM, Daniel Vetter wrote: > On Tue, Jul 22, 2014 at 4:39 PM, Christian König > wrote: >> Am 22.07.2014 16:27, schrieb Maarten Lankhorst: >> >>> op 22-07-14 16:24, Christian König schreef: >>>>> >>>>> No, you really shouldn't be doing much in the check anyway, it's meant >>>>> to be a lightweight check. If you're not ready yet because of a lockup >>>>> simply return not signaled yet. >>>> >>>> It's not only the lockup case from radeon I have in mind here. For >>>> userspace queues it might be necessary to call copy_from_user to figure out >>>> if a fence is signaled or not. >>>> >>>> Returning false all the time is probably not a good idea either. >>> >>> Having userspace implement a fence sounds like an awful idea, why would >>> you want to do that? >> >> >> Marketing moves in mysterious ways. Don't ask me, but that the direction it >> currently moves with userspace queues and IOMMU etc... > > Fence-based syncing between userspace queues submitted stuff through > doorbells and anything submitted by the general simply wont work. > Which is why I think the doorbell is a stupid interface since I just > don't see cameras and v4l devices implementing all that complexity to > get a pure userspace side sync solution. > Like it or not this is what a lot of application writers want (look at mantle and metal and similar new APIs or android synpts). Having queues and fences in userspace allows the application to structure things to best fit their own task graphs. The app can decide how to deal with dependencies and synchronization explicitly instead of blocking the queues in the kernel for everyone. Anyway, this is getting off topic. Alex From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Deucher Subject: Re: [PATCH 09/17] drm/radeon: use common fence implementation for fences Date: Tue, 22 Jul 2014 11:42:17 -0400 Message-ID: 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> <53CE6FB0.90500@canonical.com> <53CE7410.3090603@amd.com> <53CE74B5.3000201@canonical.com> <53CE77B4.6020801@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: nouveau-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "Nouveau" To: Daniel Vetter Cc: Thomas Hellstrom , nouveau , LKML , dri-devel , Ben Skeggs , "Deucher, Alexander" , =?UTF-8?Q?Christian_K=C3=B6nig?= List-Id: nouveau.vger.kernel.org T24gVHVlLCBKdWwgMjIsIDIwMTQgYXQgMTE6MTkgQU0sIERhbmllbCBWZXR0ZXIgPGRhbmllbEBm ZndsbC5jaD4gd3JvdGU6Cj4gT24gVHVlLCBKdWwgMjIsIDIwMTQgYXQgNDozOSBQTSwgQ2hyaXN0 aWFuIEvDtm5pZwo+IDxjaHJpc3RpYW4ua29lbmlnQGFtZC5jb20+IHdyb3RlOgo+PiBBbSAyMi4w Ny4yMDE0IDE2OjI3LCBzY2hyaWViIE1hYXJ0ZW4gTGFua2hvcnN0Ogo+Pgo+Pj4gb3AgMjItMDct MTQgMTY6MjQsIENocmlzdGlhbiBLw7ZuaWcgc2NocmVlZjoKPj4+Pj4KPj4+Pj4gTm8sIHlvdSBy ZWFsbHkgc2hvdWxkbid0IGJlIGRvaW5nIG11Y2ggaW4gdGhlIGNoZWNrIGFueXdheSwgaXQncyBt ZWFudAo+Pj4+PiB0byBiZSBhIGxpZ2h0d2VpZ2h0IGNoZWNrLiBJZiB5b3UncmUgbm90IHJlYWR5 IHlldCBiZWNhdXNlIG9mIGEgbG9ja3VwCj4+Pj4+IHNpbXBseSByZXR1cm4gbm90IHNpZ25hbGVk IHlldC4KPj4+Pgo+Pj4+IEl0J3Mgbm90IG9ubHkgdGhlIGxvY2t1cCBjYXNlIGZyb20gcmFkZW9u IEkgaGF2ZSBpbiBtaW5kIGhlcmUuIEZvcgo+Pj4+IHVzZXJzcGFjZSBxdWV1ZXMgaXQgbWlnaHQg YmUgbmVjZXNzYXJ5IHRvIGNhbGwgY29weV9mcm9tX3VzZXIgdG8gZmlndXJlIG91dAo+Pj4+IGlm IGEgZmVuY2UgaXMgc2lnbmFsZWQgb3Igbm90Lgo+Pj4+Cj4+Pj4gUmV0dXJuaW5nIGZhbHNlIGFs bCB0aGUgdGltZSBpcyBwcm9iYWJseSBub3QgYSBnb29kIGlkZWEgZWl0aGVyLgo+Pj4KPj4+IEhh dmluZyB1c2Vyc3BhY2UgaW1wbGVtZW50IGEgZmVuY2Ugc291bmRzIGxpa2UgYW4gYXdmdWwgaWRl YSwgd2h5IHdvdWxkCj4+PiB5b3Ugd2FudCB0byBkbyB0aGF0Pwo+Pgo+Pgo+PiBNYXJrZXRpbmcg bW92ZXMgaW4gbXlzdGVyaW91cyB3YXlzLiBEb24ndCBhc2sgbWUsIGJ1dCB0aGF0IHRoZSBkaXJl Y3Rpb24gaXQKPj4gY3VycmVudGx5IG1vdmVzIHdpdGggdXNlcnNwYWNlIHF1ZXVlcyBhbmQgSU9N TVUgZXRjLi4uCj4KPiBGZW5jZS1iYXNlZCBzeW5jaW5nIGJldHdlZW4gdXNlcnNwYWNlIHF1ZXVl cyBzdWJtaXR0ZWQgc3R1ZmYgdGhyb3VnaAo+IGRvb3JiZWxscyBhbmQgYW55dGhpbmcgc3VibWl0 dGVkIGJ5IHRoZSBnZW5lcmFsIHNpbXBseSB3b250IHdvcmsuCj4gV2hpY2ggaXMgd2h5IEkgdGhp bmsgdGhlIGRvb3JiZWxsIGlzIGEgc3R1cGlkIGludGVyZmFjZSBzaW5jZSBJIGp1c3QKPiBkb24n dCBzZWUgY2FtZXJhcyBhbmQgdjRsIGRldmljZXMgaW1wbGVtZW50aW5nIGFsbCB0aGF0IGNvbXBs ZXhpdHkgdG8KPiBnZXQgYSBwdXJlIHVzZXJzcGFjZSBzaWRlIHN5bmMgc29sdXRpb24uCj4KCkxp a2UgaXQgb3Igbm90IHRoaXMgaXMgd2hhdCBhIGxvdCBvZiBhcHBsaWNhdGlvbiB3cml0ZXJzIHdh bnQgKGxvb2sgYXQKbWFudGxlIGFuZCBtZXRhbCBhbmQgc2ltaWxhciBuZXcgQVBJcyBvciBhbmRy b2lkIHN5bnB0cykuICBIYXZpbmcKcXVldWVzIGFuZCBmZW5jZXMgaW4gdXNlcnNwYWNlIGFsbG93 cyB0aGUgYXBwbGljYXRpb24gdG8gc3RydWN0dXJlCnRoaW5ncyB0byBiZXN0IGZpdCB0aGVpciBv d24gdGFzayBncmFwaHMuICBUaGUgYXBwIGNhbiBkZWNpZGUgaG93IHRvCmRlYWwgd2l0aCBkZXBl bmRlbmNpZXMgYW5kIHN5bmNocm9uaXphdGlvbiBleHBsaWNpdGx5IGluc3RlYWQgb2YKYmxvY2tp bmcgdGhlIHF1ZXVlcyBpbiB0aGUga2VybmVsIGZvciBldmVyeW9uZS4gIEFueXdheSwgdGhpcyBp cwpnZXR0aW5nIG9mZiB0b3BpYy4KCkFsZXgKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX18KTm91dmVhdSBtYWlsaW5nIGxpc3QKTm91dmVhdUBsaXN0cy5mcmVl ZGVza3RvcC5vcmcKaHR0cDovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZv L25vdXZlYXUK