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 E93BA360 for ; Sat, 6 Jul 2024 00:12:07 +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=1720224728; cv=none; b=XivpFFpqmazFlq0k06P+nb9UomWfIPOYjPvWWVogGrzSXEtAOS+G9ruoSE+hMhl4rW9pB0zABfB7b1QRWZstgnNiUHaD4Vk5vd5nvHckZR+DF9bR4ftmeq8dK6p7g9pWpN47q1gT3cvxKEck4kxng58zYqAVs2K6QdMdX0eY5LE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720224728; c=relaxed/simple; bh=jn93tI6Ecgv8ripCCk/bBZy/npDcXNgnxyv6HSkEpag=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lFjchlJUj0+rNzaaTgiS+TigTK4w9nM/++ByFcMHc1qBxM0kes3X7QDG+07rIBuaKe0LRgD+TDsbXAITAuLsZycqMSr/vibpW9l/xXf6J0eEJqTAwIFZ+iRikHDNi+5aFXqqQq1sV7RxgBzh2wF0A/l9YKEKz6e8LtEeU+QidTE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b=DzhTaylS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="DzhTaylS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABB15C116B1; Sat, 6 Jul 2024 00:12:06 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="DzhTaylS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1720224722; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6kkzCG1yU6CNYE6GToxrNpzNj95WbzRwOqplwdV0la8=; b=DzhTaylSx/bqMBPRwXV7WIcxe4lW8lmsEETKnfwKF/lsQe9u4PbX3ReXBn+RhglNaO5Oc3 wjt/mjdxR7LSNGdglwyHMFw6FGQTyaKhwNRpos2aN8bqfE3VJK1eZgUckAp1XapCpP5mWN n7uPJZfyk2uKT+lTf2JKlznBj69vqUM= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 16013217 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Sat, 6 Jul 2024 00:12:01 +0000 (UTC) Date: Sat, 6 Jul 2024 02:11:59 +0200 From: "Jason A. Donenfeld" To: Linus Torvalds Cc: jolsa@kernel.org, mhiramat@kernel.org, cgzones@googlemail.com, brauner@kernel.org, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: deconflicting new syscall numbers for 6.11 Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Hi Linus, On Fri, Jul 05, 2024 at 12:46:37PM -0700, Linus Torvalds wrote: > If saying "the state size is fixed at 256 bytes" means that ten years > from now, we won't be updating to some super-duper fancy new algorithm > that wants to keep a huge state size - then that's a GOOD thing. I'm all for avoiding fanciness. I can imagine three plausible scenarios where we benefit from the kernel doing the allocation, rather than mmap, or where it's nice to have the kernel decide on the size: - On some platform, it's actually more efficient to generate N blocks, such that the state there needs to be larger. - The amount of state that we buffer increases according to some speed vs practicality trade off that changes. (Right now we buffer 1.5 blocks; maybe 3.5 would be better eventually.) - We find out that there's a better way of doing all this with a special mapping instead, or some other means. What I have in mind, IOW, isn't fanciness. But alright, let me run with where you're urging me and see where that takes things. > Side note: you could just stick the size as a constant in the vdso too. Yea, this sounds more like solution (4) from my last email. I'll give that a shot and see what it's like nuking the syscall. I'll ping here when v21 of the series is ready, and hopefully you like it more. Thanks for brainstorming this all with me. Jason