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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEE1CC10F1B for ; Mon, 19 Dec 2022 12:49:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231947AbiLSMs7 (ORCPT ); Mon, 19 Dec 2022 07:48:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230283AbiLSMsz (ORCPT ); Mon, 19 Dec 2022 07:48:55 -0500 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98AFBE089; Mon, 19 Dec 2022 04:48:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=qb34MAU0ZEKzBpLKg0adOlW9E7RFwMB3/UYEgFSDOn8=; b=UqSA0EsQxeAV6MF38ZT2DQ+DK4 cfZeCzYx+t3G1PSUTVKnC3o8nb1EdyExg17toHM9oEsBzv5FddcNlG1xC+038DT7GhQfdwyVmCNy6 VfKUGD3oWOr3eGMTwWfqreS21NDDbnyaQuDFAvhqHKcs36uAfbslJckOQJVtCTdj5sQuF1WQWu/R0 byufzpfTk0x/oIcUNNcaT7jtDQoQloqZEpLM//hPhjs8QTbylSggKdLP7T3PeRfm1umGjz1afgLky 1l6HRRDIFY7zsN2JKmjOuUZ+OBsRFjK6KhUR+JJ2VMzY+bi1oMbeY4ugiW1pgEhMrJtBJWcBhF/vx SoOflzuQ==; Received: from 200-158-226-94.dsl.telesp.net.br ([200.158.226.94] helo=[192.168.1.60]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1p7FZI-006Ikw-6P; Mon, 19 Dec 2022 13:48:32 +0100 Message-ID: <3ff9f56c-479b-2dbd-9ee6-c7d00c7bd285@igalia.com> Date: Mon, 19 Dec 2022 09:48:18 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH 6.0.y / 6.1.y] x86/split_lock: Add sysctl to control the misery mode To: Peter Zijlstra , Greg KH Cc: stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, corbet@lwn.net, kernel-dev@igalia.com, kernel@gpiccoli.net, fenghua.yu@intel.com, joshua@froggi.es, pgofman@codeweavers.com, pavel@denx.de, pgriffais@valvesoftware.com, zfigura@codeweavers.com, cristian.ciocaltea@collabora.com, Thomas Gleixner , Dave Hansen , Tony Luck , Andre Almeida References: <20221218234400.795055-1-gpiccoli@igalia.com> Content-Language: en-US From: "Guilherme G. Piccoli" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/12/2022 07:59, Peter Zijlstra wrote: > On Mon, Dec 19, 2022 at 11:17:39AM +0100, Greg KH wrote: > >> What specific programs have this problem and what are the exact results >> of it? > > IIRC it was God of War (2018) that triggered this initially. But it's > possible more games were found to tickle this specific thing. Since it's > binary only gunk that is unlikely to ever get fixed we need something to > allow for it. > > (slow motion Kratos yelling B...o...y...) > >> Also, this is really a new feature and not really a "fix", but one could >> argue a lot that this is a "resolve a performance problem" if you want >> to and have the numbers to back it up {hint} > > Right, there were some, they should indeed have been included. Thanks Peter, that's exactly it - the current report is linked on commit message. About performance numbers, the only "numbers" I have is: game is unplayable, according to the report "When I launch God of War through Steam or Lutris I get around 25 fps, on lowest settings and at 10% resolution scaling", FPS for for games is double of that usually. I understand this is not a regular fix in which something is completely broken, but it does fix a behavior introduced on kernel that prevent some userspace binaries to properly run, in practice. Ofc some will argue that we already have the kernel parameter, but it's different - requires reboot and bootloader understanding. If 6.0.y is too much, I'd ask we have it at least for 6.1, which is long-term, that will help a lot of people for sure. Thanks, Guilherme