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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D5621C43331 for ; Sat, 9 Nov 2019 12:57:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B068C21848 for ; Sat, 9 Nov 2019 12:57:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726492AbfKIM5C (ORCPT ); Sat, 9 Nov 2019 07:57:02 -0500 Received: from relay9-d.mail.gandi.net ([217.70.183.199]:35277 "EHLO relay9-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726267AbfKIM5B (ORCPT ); Sat, 9 Nov 2019 07:57:01 -0500 X-Originating-IP: 93.29.109.196 Received: from aptenodytes (196.109.29.93.rev.sfr.net [93.29.109.196]) (Authenticated sender: paul.kocialkowski@bootlin.com) by relay9-d.mail.gandi.net (Postfix) with ESMTPSA id 72DDFFF806; Sat, 9 Nov 2019 12:56:57 +0000 (UTC) Date: Sat, 9 Nov 2019 13:56:57 +0100 From: Paul Kocialkowski To: Stefan Monnier Cc: linux-sunxi@googlegroups.com, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [linux-sunxi] Re: [PATCH 1/3] media: cedrus: Properly signal size in mode register Message-ID: <20191109125657.GB845368@aptenodytes> References: <20191026074959.1073512-1-jernej.skrabec@siol.net> <20191026074959.1073512-2-jernej.skrabec@siol.net> <20191104100228.GD502900@aptenodytes> <7309638.L6IRxaGt1L@jernej-laptop> <20191105081034.GC584930@aptenodytes> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="gatW/ieO32f1wygP" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --gatW/ieO32f1wygP Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Stefan, On Thu 07 Nov 19, 09:24, Stefan Monnier wrote: > > Do you know if we have a way to report some estimation of the maximum s= upported > > fps to userspace? It would be useful to let userspace decide whether it= 's a > > better fit than software decoding. >=20 > Even if the fps ends up too low for the player's taste, I can't imagine > why software decoding would be preferable: it seems it could be only > even (substantially) slower. Or are there speed-up options in software > decoding not available in hardware decoding (such as playing only every > N'th frame, maybe?). This may be true for the Allwinner case as we know it today but not true in general. It could happen that the CPU is perfectly able to decode as fast a= s or faster than the hardware implementation, but userspace would still try to u= se hardware video decoding when it can provide good enough performance so that= the CPU can do other things in the meantime. Having a good idea of the expected performance is important for userspace to make this kind of policy decision. This is kind of a common misconception that hardware offloading always impl= ies a performance improvment. In our cases where the CPU is a bottleneck, it is more often true than not, but this is by far not true in general. Cheers, Paul --=20 Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com --gatW/ieO32f1wygP Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEJZpWjZeIetVBefti3cLmz3+fv9EFAl3Gt5gACgkQ3cLmz3+f v9G+SQf/VkRK362zU+fWkU5EBkELTY0Sc9p6L4QbI9EJuQxHG4d6HimlPe7D2d8N QVMKBoyL5Sy1bH02gwOwdqiCDWLdJRhLVqT0utO102Hl0kTA4///BZPXhPg+9eLX Uw/gQA7tXTMH2qeT+VcP8DjcB9GKpFw4o5gpwDG1d/UE+hPBfKvqtI4zhh/GFz/l FfXxD/SrAlDzjJQiHjxVGWSuqXn7GI/zoxV9r/A13WT1axiLgXt96RtiMZuIXg+4 FIS3K0LKB92gNA/eQYbwPCQjtrumoTA6r32t/zNzPDIRNE5J+fN53iSpcpB4pJfP 41eUPKEtTNQyum2cmUj3e50dl3+wWQ== =/o/m -----END PGP SIGNATURE----- --gatW/ieO32f1wygP--