From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 380821BC2A for ; Fri, 10 May 2024 08:25:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715329542; cv=none; b=ozlqIVcZLqAhoK3Osm9dR90JdFYwr+zf6f65LnhCX7/t7qLmzVjGe7P2alkvEcMzhU5N2nhCzxa1DQfjclfBG9gXyuk7FDO9Sv75Jh9MiRr1W42ow8wDy1s9Na/08th4GpJa95D7iJBivPhF3fp1oan8CgMDps9pbjDkCp9YMUI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715329542; c=relaxed/simple; bh=x7eOLArKZlJ6Jjdv6wdjIvSJbMgG4/RroQBS+sVq94A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Hf23Amt0vwnUQ3aEdMLPdh9fv6Pb8IUS7JlYgSOuPlcf4uA7yZ4djAHR6kCs2FsHn+y6ryWaQE0XLc5izcdo6pscoKSwI5IJ/DKje3urDUVX/v4l0b6U36MJLiDuZiMvFFyFEmaFilGnPU+Kv0Sry/SaGC/IZcaBqCi+N8Dzcv0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IvX2y8ZJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IvX2y8ZJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 210FFC113CC; Fri, 10 May 2024 08:25:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715329541; bh=x7eOLArKZlJ6Jjdv6wdjIvSJbMgG4/RroQBS+sVq94A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IvX2y8ZJLu3RkYqJQvbbcfiofmJLuXo21dv+0w1PP6AlhjElmbUmTWBcJJrFwvX6z TYbMWTxPHVB8/qwTRmfUfsOakuPE3H+qCB1swBQKz+6VrAfxpixQbMvDODiGu2BD2v /neuwXES6X9NQfx/fbQ5dRuJFrULKWHh1ixC4xcQVOZZV7DNzvZlLJ/hQq8DovubR5 Y6Nui23vJGpF4M5ZixJVHqGUfQlFqkl0sjFvf+vh2dWrk90McnfW5e8TOGvekx5xhB 7K7lFembeD4k211WzPEYLmn/CE22TvH62rysGn/qy4qK1m2aJv6bZeVkPtnRq/Bx1p 4UdPP3KDnzRcQ== Date: Fri, 10 May 2024 09:25:37 +0100 From: Conor Dooley To: Charlie Jenkins Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Song Liu , Xi Wang , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , =?iso-8859-1?Q?Cl=E9ment_L=E9ger?= , Jessica Clarke , Andy Chiu , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/8] riscv: Support compiling the kernel with more extensions Message-ID: <20240510-okay-trade-8826cb134979@spud> References: <20240507-compile_kernel_with_extensions-v2-0-722c21c328c6@rivosinc.com> <20240509-uptown-aging-5bdec4730d70@spud> <20240509-google-passing-3e7577235c44@spud> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="EwfUi93w0+FmVOuD" Content-Disposition: inline In-Reply-To: --EwfUi93w0+FmVOuD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 09, 2024 at 03:55:12PM -0700, Charlie Jenkins wrote: > On Thu, May 09, 2024 at 11:08:34PM +0100, Conor Dooley wrote: > > Maybe if you read what I wrote you'd see what I was getting at, or maybe > > not as I might not have been sufficiently clear. I'm not saying that th= is > > particular optimisation is not worth having, but rather than I wanted to >=20 > I seem to frequently give you the impression that I don't read what you > say before responding. Does it happen frequently? I don't really recall it annoying me before. > What we each view as "important" in the kernel is > different so we come from different places when approaching a problem. I > respond in the way that I do not because I am not listening to you, but > simply because I have a different opinion and I am not explaining that > properly. If you're trying to describe a different opinion, responding to the bit I was talking about, as you do below in your latest response is ideal. Responding inline but not actually addressing the points I was making did make me think you were [un]intentionally ignoring what I was trying to say. > > see why this particular optimisation was worth maintaining 3 code paths >=20 > I interpreted the "3 code paths" as with Zbb + 64 bit, with Zbb + 32 > bit, and without Zbb. I directly responded to that by saying that we > could eliminate all of the code paths that are not Zbb + 64 bit could be > eliminated. I should have given performance numbers for these alternate > cases too, and somebody should have asked. I agree that performance > needs justification, and I understand that I did not provide ample > justification in this patch. All other architectures optimized these > code paths so I figured that was sufficient justification for riscv to > do the same, but I understand that it is not. And hey, if you look at the commit in question, who acked it? I'm just saying that I think we should have a higher standard going forwards. > > for but the commit message does not detail any of the benefits, and > > looking at the cover I discovered that it was not tested in hardware nor > > seemingly with a real test case. >=20 > It's hard when riscv currently is very focused on microcontrollers. Zbb is actually implemented in hardware, so testing it in the real world is not a barrier. Palmer probably has a JH7110 board that someone gave to him is not using... > These changes are in order to help future hardware that is more focused > about performance. I'm not replying to most of your response rn, got other stuff to do, but what I was trying to say is that I think the point at which optimisations for future hardware/extensions should be merged is the point at which those extensions are no longer future. > That's why I contribute this upstream with the hope > that other people, like me, care about performance. Heh, that could be read to mean that I do not care about performance, which wouldn't be true. Cheers, Conor. --EwfUi93w0+FmVOuD Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZj3aAAAKCRB4tDGHoIJi 0nK5AQCoDMSe9DzUyhpQR58HC2BsiABcEwTWZgGhSBBKbfG+FgD+LfsnoPklGhGT eJ6+WpbCfqceocD7hR5oKi+JaTKMMAs= =9cVI -----END PGP SIGNATURE----- --EwfUi93w0+FmVOuD--