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 532CFCDB46E for ; Thu, 12 Oct 2023 14:37:22 +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=R28XbtN4w5zHM2ExiQujkLrZkfYc2mQNICEZCFB9VDw=; b=iWo/Ugo7MPyWLcq78pMroimK49 wR6TQAwpuLOQn634pd2ITcUGpv6zZ/Lu6mbT2iYMYHNnIS6l4x9quOHrjNK5Vw+GyRm7wcp/NwefL KdGPUc4tKI87ER640Up3V/u9vX7Ez6fakzGEit8H7Ml/o/BtAu8aRD41XYMwlgUZfvacdKkPDyyh0 JiewiICiyMzPfyxNUobDreUF3M+oCaFKQ6G6HCyNKaPviieAMLRb4iRoHuwihoXsxjBiRW7nwlFRE pR0dYJAjS6Zk97lmxSXiHtB9x0abih9O/w4vltYqnpWZah6Z+ps6xmDFhkswrf5uhW7FIBPFyfxxs yPEQhQZg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qqwoK-001CNt-0u; Thu, 12 Oct 2023 14:37:12 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qqwoF-001CKf-1F for linux-riscv@lists.infradead.org; Thu, 12 Oct 2023 14:37:10 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id DBC0CB824C2; Thu, 12 Oct 2023 14:36:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81DA8C433C7; Thu, 12 Oct 2023 14:36:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697121417; bh=tqPqmHok1AyU/GG626kkM4PFGH7XQeQEOYooofFbE+Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BMAjov1X2fVRTyegaWW28iHtNCwbmTe1ER+CCckjzVHEl8moiISR5Ys0Ad3QBESNC XCzNCnYLVTCqKSaKM+X5dbQ2oQl+p2lhzVyGRJsx9HwFVTyNZp6hYbj2fa7b8H5Sy/ 3n81yeRGgGcmV45bY/mg97c7o6NNjMa/NIXvkR4apDIyYaVJ+nwDo/YyMLqmrx8Wil nssBNW5fPPVUqURzE76CFjUp/JAzjV5vThzwy8HIRpmt8FpQ3euJxC1qiF9Qrwl8iI THEa9ERLSlWS/JtSVovdCGce8bL3D1XBQ35AbEWpKtQJsSEbs4nHjn1kZTBV1jil2W SLIyA23D6wRCA== Date: Thu, 12 Oct 2023 15:36:53 +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 v3 1/2] riscv: errata: thead: use riscv_nonstd_cache_ops for CMO Message-ID: <20231012-pranker-usage-09a85a36356f@spud> References: <20231012141456.4078-1-jszhang@kernel.org> <20231012141456.4078-2-jszhang@kernel.org> MIME-Version: 1.0 In-Reply-To: <20231012141456.4078-2-jszhang@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231012_073707_645984_1DFA67AF X-CRM114-Status: GOOD ( 13.77 ) 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="===============3519019621723201208==" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org --===============3519019621723201208== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="tLH7qnMb79tGa+m2" Content-Disposition: inline --tLH7qnMb79tGa+m2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Oct 12, 2023 at 10:14:55PM +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 =46rom v2: Reviewed-by: Conor Dooley Thanks, Conor. --tLH7qnMb79tGa+m2 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZSgEhQAKCRB4tDGHoIJi 0oQqAP9E3GPMvuDoXMFDfJdL0fEkQ1D91Q115ThR1vWUqlcKCwEAmZexxPc2Ytz3 XSpUhcOVF4jxrEhP3FjNPNvYpXJp6wg= =NXCq -----END PGP SIGNATURE----- --tLH7qnMb79tGa+m2-- --===============3519019621723201208== 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 --===============3519019621723201208==--