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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7961BE7849A for ; Mon, 2 Oct 2023 10:55:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Reply-To:Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date :Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lYRoQRjoWGEHu32Z1agPMeJTDU0ntyX+sazSDkh2OGE=; b=i6xXfnvAXP/c3F8/3lN73B2jDC YgGsHaNuIP7JSBxW8z+UnvGqjfRkPmJXDGvcb/iHeo9r5XHFB6ZVQb89WsT6uZcB/ClDYXsZ4BtGl V0tBAA+cPxploaW0QHR7rMR+3gXlrT49U6lH1U4dTIhSqy1no/zsqBmCfSAaZU1I30W7yFPRKGWRj oGTmdfWoTILNwmnC7UAf4OgXtu/X+5zLR+1MMWSCXV1IErFqHZHojA+1A2De5iKwgfUKhITWWLk0A VVBumoTqagyX9ypgLYUkwF4eX8WGS/rPdewWVyJCucv70BW4VsL1aCPIeRfLCSHQHNbNBymw60u5V bcIzlyog==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qnGaR-00CUzH-14; Mon, 02 Oct 2023 10:55:39 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qnGaO-00CUyD-2q for linux-riscv@lists.infradead.org; Mon, 02 Oct 2023 10:55:38 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id ED28C60DC1; Mon, 2 Oct 2023 10:55:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA2DBC433C8; Mon, 2 Oct 2023 10:55:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696244135; bh=F5fHvFLRPSXGAJr5Hur9dBSrn1AlR9jGY19xXDVZ+To=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ebkPo+WRr0ngMFnObD+G/SsGSqtuAZEKlpHHoqkawi7RHXBd0sxsUG1QkXKc4cspE yXV9hVW556TzPBMhNay2gmLR0xCSP7cTqvz24ZSxXFPJHxS7EbVrLlkbu5tPn/va28 KiRrn96lV6TFqopL8izAFIlDB1GsqBvOqDGZbicqpaER2bm9y9z60L/vIcN48UqDMr ldNgeV+OVuCnO8knQ+oMMYiDA8FCXzE1s/WQCoYF6JqHlaCnS6Q9U7ae2hcazzxqQP 7HD6J9uiy4kr71HI+xrd4V1XoE+8q8CmsuaLjEAQr3KbLmBTmTaQA+bP9OVyYNXc5U 3E2ep5dWxtknw== Date: Mon, 2 Oct 2023 11:55:31 +0100 From: Conor Dooley To: Jisheng Zhang Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Emil Renner Berthing Subject: Re: [PATCH v2 1/2] riscv: errata: thead: use riscv_nonstd_cache_ops for CMO Message-ID: <20231002-angles-utopia-6c6c7b18231e@spud> References: <20231001103433.3187-1-jszhang@kernel.org> <20231001103433.3187-2-jszhang@kernel.org> MIME-Version: 1.0 In-Reply-To: <20231001103433.3187-2-jszhang@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231002_035536_963065_CB56881D X-CRM114-Status: GOOD ( 14.60 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============1460728414589532236==" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org --===============1460728414589532236== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="U/Lf1c64QYsza03U" Content-Disposition: inline --U/Lf1c64QYsza03U Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Oct 01, 2023 at 06:34:32PM +0800, Jisheng Zhang wrote: > Previously, we use alternative mechanism to dynamically patch > the CMO operations for THEAD C906/C910 during boot for performance > reason. But as pointed out by Arnd, "there is already a significant > cost in accessing the invalidated cache lines afterwards, which is > likely going to be much higher than the cost of an indirect branch". > And indeed, there's no performance difference with GMAC and EMMC per > my test on Sipeed Lichee Pi 4A board. >=20 > Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify > the alternative code, and to acchieve Arnd's goal -- "I think > moving the THEAD ops at the same level as all nonstandard operations > makes sense, but I'd still leave CMO as an explicit fast path that > avoids the indirect branch. This seems like the right thing to do both > for readability and for platforms on which the indirect branch has a > noticeable overhead." >=20 > Signed-off-by: Jisheng Zhang > Tested-by: Emil Renner Berthing Reviewed-by: Conor Dooley Thanks, Conor. --U/Lf1c64QYsza03U Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZRqhowAKCRB4tDGHoIJi 0piXAP9YVt+cUOHo4WTwqUZ7/v9f9zmKv0aMbkueUtWc8W5O7QD/RBTXAJXMS6mi pEEyPYGX00rO85GTDF1mlRpvqiiPKAA= =KGQg -----END PGP SIGNATURE----- --U/Lf1c64QYsza03U-- --===============1460728414589532236== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv --===============1460728414589532236==--