From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH v2] drm/vc4: Add a debugfs entry to disable/enable the load tracker Date: Sun, 2 Dec 2018 08:14:40 +0100 Message-ID: <20181202081440.0ec235c4@bbrezillon> References: <20181130161104.16352-1-paul.kocialkowski@bootlin.com> <87r2f2patf.fsf@anholt.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail.bootlin.com (mail.bootlin.com [62.4.15.54]) by gabe.freedesktop.org (Postfix) with ESMTP id 191BE6E16D for ; Sun, 2 Dec 2018 07:14:42 +0000 (UTC) In-Reply-To: <87r2f2patf.fsf@anholt.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Eric Anholt Cc: David Airlie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Paul Kocialkowski , Maxime Ripard , Thomas Petazzoni List-Id: dri-devel@lists.freedesktop.org T24gRnJpLCAzMCBOb3YgMjAxOCAxMjozMDo1MiAtMDgwMApFcmljIEFuaG9sdCA8ZXJpY0Bhbmhv bHQubmV0PiB3cm90ZToKCj4gUGF1bCBLb2NpYWxrb3dza2kgPHBhdWwua29jaWFsa293c2tpQGJv b3RsaW4uY29tPiB3cml0ZXM6Cj4gCj4gPiBJbiBvcmRlciB0byB0ZXN0IHdoZXRoZXIgdGhlIGxv YWQgdHJhY2tlciBpcyB3b3JraW5nIGFzIGV4cGVjdGVkLCB3ZQo+ID4gbmVlZCB0aGUgYWJpbGl0 eSB0byBjb21wYXJlIHRoZSBjb21taXQgcmVzdWx0IHdpdGggdGhlIHVuZGVycnVuCj4gPiBpbmRp Y2F0aW9uLiBXaXRoIHRoZSBsb2FkIHRyYWNrZXIgYWx3YXlzIGVuYWJsZWQsIGNvbW1pdHMgdGhh dCBhcmUKPiA+IGV4cGVjdGVkIHRvIHRyaWdnZXIgYW4gdW5kZXJydW4gYXJlIGFsd2F5cyByZWpl Y3RlZCwgc28gdXNlcnNwYWNlCj4gPiBjYW5ub3QgZ2V0IHRoZSBhY3R1YWwgdW5kZXJydW4gaW5k aWNhdGlvbiBmcm9tIHRoZSBoYXJkd2FyZS4KPiA+Cj4gPiBBZGQgYSBkZWJ1Z2ZzIGVudHJ5IHRv IGRpc2FibGUvZW5hYmxlIHRoZSBsb2FkIHRyYWNrZXIsIHNvIHRoYXQgYSBEUk0KPiA+IGNvbW1p dCBleHBlY3RlZCB0byB0cmlnZ2VyIGFuIHVuZGVycnVuIGNhbiBnbyB0aHJvdWdoIHdpdGggdGhl IGxvYWQKPiA+IHRyYWNrZXIgZGlzYWJsZWQuIFRoZSB1bmRlcnJ1biBpbmRpY2F0aW9uIGlzIHRo ZW4gYXZhaWxhYmxlIHRvCj4gPiB1c2Vyc3BhY2UgYW5kIGNhbiBiZSBjaGVja2VkIGFnYWluc3Qg dGhlIGNvbW1pdCByZXN1bHQgd2l0aCB0aGUgbG9hZAo+ID4gdHJhY2tlciBlbmFibGVkLgo+ID4K PiA+IFNpZ25lZC1vZmYtYnk6IFBhdWwgS29jaWFsa293c2tpIDxwYXVsLmtvY2lhbGtvd3NraUBi b290bGluLmNvbT4gIAo+IAo+IEdpdmVuIHRoYXQgdGhlIGxvYWQgdHJhY2tlciBpcyBnb2luZyB0 byBiZSBjb25zZXJ2YXRpdmUgYW5kIHNheSB0aGluZ3MKPiB3aWxsIHVuZGVycnVuIGV2ZW4gd2hl biB0aGV5IG1pZ2h0IG5vdCBpbiBwcmFjdGljZSwgd2lsbCB0aGlzIGFjdHVhbGx5Cj4gYmUgdXNl ZnVsIGZvciBhdXRvbWF0ZWQgdGVzdGluZz8gT3IgaXMgdGhlIGludGVudCB0byBtYWtlIGl0IGVh c2llciB0bwo+IHR1bmUgdGhlIGxvYWQgdHJhY2tlciBieSBkaXNhYmxpbmcgaXQgc28gdGhhdCB5 b3UgY2FuIGV4cGVyaW1lbnQgZnJlZWx5PwoKWWVzLCB0aGF0J3Mgb25lIGdvYWwsIHRob3VnaCBJ J20gbm90IHN1cmUgSUdUIGlzIHN1cHBvc2VkIHRvIGNvbnRhaW4Kc3VjaCBkZWJ1Z2dpbmcgdG9v bHMuIEJ1dCB0aGUgbWFpbiBiZW5lZml0IGlzIGJlaW5nIGFibGUgdG8gdHJhY2sKcmVncmVzc2lv bnMgaW4gdGhlIGxvYWQgdHJhY2tpbmcgYWxnbyB0aGF0IG1ha2VzIGl0IG1vcmUgKHRvbz8pCmNv bnNlcnZhdGl2ZS4gSSB0aGluayBwZW9wbGUgd29uJ3QgbGlrZSB0aGlzIHNvcnQgb2YgcmVncmVz c2lvbnMuIFRoZQppZGVhIHdvdWxkIGJlIHRvIHNldHRsZSBvbiBhbiBhY2NlcHRhYmxlIGxvYWQg dHJhY2tpbmcgYWxnbyAobWF5YmUKYWZ0ZXIgcmVmaW5pbmcgdGhlIHByb3Bvc2VkIG9uZSksIHJl Y29yZCB0aGUgcmVzdWx0cyAoYm90aCBnb29kIGFuZCB0b28KY29uc2VydmF0aXZlIHByZWRpY3Rp b25zKSBhbmQgdXNlIHRoYXQgYXMgYSByZWZlcmVuY2UgZm9yIHRoZSBJR1QKdGVzdC4gIApfX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFp bGluZyBsaXN0CmRyaS1kZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5m cmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40898C04EB8 for ; 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Sun, 2 Dec 2018 08:14:41 +0100 (CET) Date: Sun, 2 Dec 2018 08:14:40 +0100 From: Boris Brezillon To: Eric Anholt Cc: Paul Kocialkowski , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, David Airlie , Maxime Ripard , Thomas Petazzoni Subject: Re: [PATCH v2] drm/vc4: Add a debugfs entry to disable/enable the load tracker Message-ID: <20181202081440.0ec235c4@bbrezillon> In-Reply-To: <87r2f2patf.fsf@anholt.net> References: <20181130161104.16352-1-paul.kocialkowski@bootlin.com> <87r2f2patf.fsf@anholt.net> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 30 Nov 2018 12:30:52 -0800 Eric Anholt wrote: > Paul Kocialkowski writes: > > > In order to test whether the load tracker is working as expected, we > > need the ability to compare the commit result with the underrun > > indication. With the load tracker always enabled, commits that are > > expected to trigger an underrun are always rejected, so userspace > > cannot get the actual underrun indication from the hardware. > > > > Add a debugfs entry to disable/enable the load tracker, so that a DRM > > commit expected to trigger an underrun can go through with the load > > tracker disabled. The underrun indication is then available to > > userspace and can be checked against the commit result with the load > > tracker enabled. > > > > Signed-off-by: Paul Kocialkowski > > Given that the load tracker is going to be conservative and say things > will underrun even when they might not in practice, will this actually > be useful for automated testing? Or is the intent to make it easier to > tune the load tracker by disabling it so that you can experiment freely? Yes, that's one goal, though I'm not sure IGT is supposed to contain such debugging tools. But the main benefit is being able to track regressions in the load tracking algo that makes it more (too?) conservative. I think people won't like this sort of regressions. The idea would be to settle on an acceptable load tracking algo (maybe after refining the proposed one), record the results (both good and too conservative predictions) and use that as a reference for the IGT test.