From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 752126E09F for ; Mon, 18 Oct 2021 07:43:14 +0000 (UTC) References: <20211015233845.12272-1-ashutosh.dixit@intel.com> <7fee0739-2ef5-f6c7-84fd-e73c9a8085f2@intel.com> <877deddfhs.wl-ashutosh.dixit@intel.com> <8d13e90a-04e8-47df-c2f5-a3afce04711a@intel.com> From: Tvrtko Ursulin Message-ID: <784e8917-05cc-c5ed-ef98-dc21edda789b@linux.intel.com> Date: Mon, 18 Oct 2021 08:43:10 +0100 MIME-Version: 1.0 In-Reply-To: <8d13e90a-04e8-47df-c2f5-a3afce04711a@intel.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [igt-dev] [PATCH i-g-t] lib/i915: Fix gem_has_execlists to match description List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: igt-dev-bounces@lists.freedesktop.org Sender: "igt-dev" To: John Harrison , "Dixit, Ashutosh" Cc: igt-dev@lists.freedesktop.org List-ID: On 16/10/2021 00:57, John Harrison wrote: > On 10/15/2021 16:39, Dixit, Ashutosh wrote: >> On Fri, 15 Oct 2021 16:42:12 -0700, John Harrison wrote: >>> On 10/15/2021 16:38, Ashutosh Dixit wrote: >>>> Driver is using execlists if it is not using GuC submission. >>>> GEM_SUBMISSION_EXECLISTS flag indicates if execlist submission is >>>> available, not if it is being used by the driver. >>>> >>>> Signed-off-by: Ashutosh Dixit >>>> --- >>>>    lib/i915/gem_submission.c | 2 +- >>>>    1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/lib/i915/gem_submission.c b/lib/i915/gem_submission.c >>>> index 2627b802cfb..4312a73bd85 100644 >>>> --- a/lib/i915/gem_submission.c >>>> +++ b/lib/i915/gem_submission.c >>>> @@ -153,7 +153,7 @@ bool gem_has_semaphores(int fd) >>>>     */ >>>>    bool gem_has_execlists(int fd) >>>>    { >>>> -    return gem_submission_method(fd) & GEM_SUBMISSION_EXECLISTS; >>>> +    return !gem_has_guc_submission(fd); >>> Don't we use ring submission on older platforms? >> Hmm, I wasn't aware that there was yet another submission method :/ >> >> So execlist submission is only available for gen >= 8 as the code >> says, in >> case anyone knows? > Yes. Execlists was new feature of the hardware not all that long ago > (ELSP and all that). Gen8 sounds plausible. Yes Gen8+. > Of course, it all depends why the code is asking the question? Does it > really need to know what the submission hardware is? Or is it actually > asking about the scheduling algorithm (as is the case for > gem_exec_fair). Or something else entirely? The scheduler question is > going to change again when we move to using the DRM scheduler instead of > our own private one in the execlist code. Currently though, I would > assume we use the execlist scheduler for ring submission but certainly > not for GuC submission (because the scheduler is in the hardware). Nope, no scheduling with ringbuffer backend. There is I915_PARAM_HAS_SCHEDULER and respective IGT helpers to query what kind of scheduling is supported on the device in question. It will be on a test per test basis why it is asking the question and what would be the appropriate test. Regards, Tvrtko > > John. > >> >>> Isn't the better fix to just not set the EXECLIST flag when GuC >>> submission is detected? >> Yes, let me post this patch too. Thanks! >