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Mon, 9 Sep 2019 14:12:42 +0000 (UTC) Subject: Re: [LKP] [drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression To: Feng Tang Cc: Rong Chen , Stephen Rothwell , michel@daenzer.net, lkp@01.org, linux-kernel@vger.kernel.org, dri-devel References: <20190812072545.GA63191@shbuild999.sh.intel.com> <20190813093616.GA65475@shbuild999.sh.intel.com> <64d41701-55a4-e526-17ae-8936de4bc1ef@suse.de> <20190824051605.GA63850@shbuild999.sh.intel.com> <1b897bfe-fd40-3ae3-d867-424d1fc08c44@suse.de> <44029e80-ba00-8246-dec0-fda122d53f5e@suse.de> <90e78ce8-d46a-5154-c324-a05aa1743c98@intel.com> <2e1b4d65-d477-f571-845d-fa0a670859af@suse.de> <20190904062716.GC5541@shbuild999.sh.intel.com> From: Thomas Zimmermann Openpgp: preference=signencrypt Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNKFRob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmNvbT7CwJQEEwEIAD4W IQRyF/usjOnPY0ShaOVoDcEdUwt6IwUCWznTtgIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgID AQIeAQIXgAAKCRBoDcEdUwt6I7D7CACBK42XW+7mCiK8ioXMEy1NzGbXC51RzGea8N83oEJS 1KVUtQxrkDxgrW/WLSl/TfqHFsJpdEFOv1XubWbleun3uKPy0e5vZCd5UjZPkeNjnqfCYTDy hVVsdOuFbtWDppJyJrThLqr9AgSFmoCNNUt1SVpYEEOLNE6C32BhlnSq21VLC+YXTgO/ZHTa YXkq54hHj63jwrcjkBSCkXLh37kHeqnl++GHpN+3R+o3w2OpwHAlvVjdKPT27v1tVkiydsFG 65Vd0n3m/ft+IOrGgxQM1C20uqKvsZGB4r3OGR50ekAybO7sjEJJ1Obl4ge/6RRqcvKz4LMb tGs85D6tPIeFzsBNBFs50uABCADGJj+DP1fk+UWOWrf4O61HTbC4Vr9QD2K4fUUHnzg2B6zU R1BPXqLGG0+lzK8kfYU/F5RjmEcClsIkAaFkg4kzKP14tvY1J5+AV3yNqcdg018HNtiyrSwI E0Yz/qm1Ot2NMZ0DdvVBg22IMsiudQ1tx9CH9mtyTbIXgACvl3PW2o9CxiHPE/bohFhwZwh/ kXYYAE51lhinQ3oFEeQZA3w4OTvxSEspiQR8dg8qJJb+YOAc5IKk6sJmmM7JfFMWSr22satM 23oQ3WvJb4RV6HTRTAIEyyZS7g2DhiytgMG60t0qdABG5KXSQW+OKlZRpuWwKWaLh3if/p/u 69dvpanbABEBAAHCwHwEGAEIACYWIQRyF/usjOnPY0ShaOVoDcEdUwt6IwUCWznS4AIbDAUJ A8JnAAAKCRBoDcEdUwt6I6X3CACJ8D+TpXBCqJE5xwog08+Dp8uBpx0T9n1wE0GQisZruACW NofYn8PTX9k4wmegDLwt7YQDdKxQ4+eTfZeLNQqWg6OCftH5Kx7sjWnJ09tOgniVdROzWJ7c VJ/i0okazncsJ+nq48UYvRGE1Swh3A4QRIyphWX4OADOBmTFl9ZYNPnh23eaC9WrNvFr7yP7 iGjMlfEW8l6Lda//EC5VpXVNza0xeae0zFNst2R9pn+bLkihwDLWxOIyifGRxTqNxoS4I1aw VhxPSVztPMSpIA/sOr/N/p6JrBLn+gui2K6mP7bGb8hF+szfArYqz3T1rv1VzUWAJf5Wre5U iNx9uqqx Message-ID: <6806e973-4cf7-bcac-54b4-4fac21698ece@suse.de> Date: Mon, 9 Sep 2019 16:12:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190904062716.GC5541@shbuild999.sh.intel.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="OghadfcRL1Pt0IHP3lIOLZqSfLuo3H0Bn" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --OghadfcRL1Pt0IHP3lIOLZqSfLuo3H0Bn Content-Type: multipart/mixed; boundary="b7WbaORTxilxycXJuBGn51oxVbT81WZtM"; protected-headers="v1" From: Thomas Zimmermann To: Feng Tang Cc: Rong Chen , Stephen Rothwell , michel@daenzer.net, lkp@01.org, linux-kernel@vger.kernel.org, dri-devel Message-ID: <6806e973-4cf7-bcac-54b4-4fac21698ece@suse.de> Subject: Re: [LKP] [drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression References: <20190812072545.GA63191@shbuild999.sh.intel.com> <20190813093616.GA65475@shbuild999.sh.intel.com> <64d41701-55a4-e526-17ae-8936de4bc1ef@suse.de> <20190824051605.GA63850@shbuild999.sh.intel.com> <1b897bfe-fd40-3ae3-d867-424d1fc08c44@suse.de> <44029e80-ba00-8246-dec0-fda122d53f5e@suse.de> <90e78ce8-d46a-5154-c324-a05aa1743c98@intel.com> <2e1b4d65-d477-f571-845d-fa0a670859af@suse.de> <20190904062716.GC5541@shbuild999.sh.intel.com> In-Reply-To: <20190904062716.GC5541@shbuild999.sh.intel.com> --b7WbaORTxilxycXJuBGn51oxVbT81WZtM Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Am 04.09.19 um 08:27 schrieb Feng Tang: > Hi Thomas, >=20 > On Wed, Aug 28, 2019 at 12:51:40PM +0200, Thomas Zimmermann wrote: >> Hi >> >> Am 28.08.19 um 11:37 schrieb Rong Chen: >>> Hi Thomas, >>> >>> On 8/28/19 1:16 AM, Thomas Zimmermann wrote: >>>> Hi >>>> >>>> Am 27.08.19 um 14:33 schrieb Chen, Rong A: >>>>> Both patches have little impact on the performance from our side. >>>> Thanks for testing. Too bad they doesn't solve the issue. >>>> >>>> There's another patch attached. Could you please tests this as well?= >>>> Thanks a lot! >>>> >>>> The patch comes from Daniel Vetter after discussing the problem on I= RC. >>>> The idea of the patch is that the old mgag200 code might display muc= h >>>> less frames that the generic code, because mgag200 only prints from >>>> non-atomic context. If we simulate this with the generic code, we sh= ould >>>> see roughly the original performance. >>>> >>>> >>> >>> It's cool, the patch "usecansleep.patch" can fix the issue. >> >> Thank you for testing. But don't get too excited, because the patch >> simulates a bug that was present in the original mgag200 code. A >> significant number of frames are simply skipped. That is apparently th= e >> reason why it's faster. >=20 > Thanks for the detailed info, so the original code skips time-consuming= > work inside atomic context on purpose. Is there any space to optmise it= ? > If 2 scheduled update worker are handled at almost same time, can one b= e > skipped? We discussed ideas on IRC and decided that screen updates could be synchronized with vblank intervals. This may give some rate limiting to the output. If you like, you could try the patch set at [1]. It adds the respective code to console and mgag200. Best regards Thomas [1] https://lists.freedesktop.org/archives/dri-devel/2019-September/234850.ht= ml >=20 > Thanks, > Feng >=20 >> >> Best regards >> Thomas --=20 Thomas Zimmermann Graphics Driver Developer SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany GF: Felix Imend=C3=B6rffer, Mary Higgins, Sri Rasiah HRB 21284 (AG N=C3=BCrnberg) --b7WbaORTxilxycXJuBGn51oxVbT81WZtM-- --OghadfcRL1Pt0IHP3lIOLZqSfLuo3H0Bn Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEchf7rIzpz2NEoWjlaA3BHVMLeiMFAl12XdUACgkQaA3BHVML eiP39wgAhj5qgMm7uHo8dffCx5/RrEV1TPzaPcuruhI+cIB0ULF8ZeFJ5O4PpxmN S3Z1hh4q3m7jRlJ8WOFxfqHLFy4iU1fGFL99M7lHitoHLIttmvRC9Qa3yA4v3Z6z tD+f+/Ozm954vgKhlkEadsmF8VvkeOLn6XX8O+JVg+rxpDMmEBVoCnYWDjys+N4j 7MVEHnKVHe3Hf1vZVCa69NClsvpjRSdNuASdQzqjuwjYDFDYWgrQWXkFl4sBrmn7 6CKSCbfRbkBfB739vB3WlK3X9RNwKzK62TnwJJptRtT62lDXLlBtBwC2MsBiBGh7 V9FOYDlUTxKUWf7BcUN1JjU7/Kl4dw== =WP66 -----END PGP SIGNATURE----- --OghadfcRL1Pt0IHP3lIOLZqSfLuo3H0Bn--