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 F0AF5C02198 for ; Wed, 12 Feb 2025 09:18:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: 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=gkKkfn9RZYpOXUy1js9dF0h3N+oOvgZyHXslAX7StVo=; b=4sTJ6na5JCWBz7FqrVoONjaYgd j3hNzMAducvNzY7YyffRPL8TjM/ZSX/oh3PKIGZCgE2tWeq6KkELaOJ3CLHpTH95sNeGxP/JSuJCO 0UyBtXY0YycPeY6hl83Q5kPUnkrzjpeDAAu3y+rrV9eIlthBxlGKHYU5sERd6aL2Mj++KCSNXeCky MUF4SVFx4C8XASHgyktZAXJFTQiroumyGz+CoCYU3Uf3LzVmdoCOI1AmVWTh7u67febFQOD3DZsqO SF4M0tKwDcGVGeoQ/FiL+UvotbW1x5/r4wxCLWyDnHqFUqCkBTlBWUtXCFPgPQC8iHcjBKfYo//P5 pOIng2+Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1ti8tH-00000006kTf-3TyV; Wed, 12 Feb 2025 09:18:43 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1ti8rs-00000006kME-2ka0 for linux-arm-kernel@bombadil.infradead.org; Wed, 12 Feb 2025 09:17:16 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=gkKkfn9RZYpOXUy1js9dF0h3N+oOvgZyHXslAX7StVo=; b=UvcHBjIDImLXSx122KLXeXB+E7 KoiVbl31dYtUDknrBK4nf6zhgFUWUwgwT/mfOM/gnDaFxOiUbNkgP9faSkIjm+Oext0WTZq7SRlrK sWUCc9t7y/xQJSU3/1SWptUTKdjIlVpiqV5LZ6UxqvFB99v3QIrnurJ8IyruxiPlfmW5TGK1kXuF8 /5aamdyGGzsF0N7IgLRO5gHq/mTOSyYv/qYNqZvnGx3zXW4jFy0byilRTeYxhNOwY2qSCAByfsw10 xwVU34JD6NiBG4a6X4h1tiwEYGeu856iOp+k165oP6S6JCwFj0epHoo8aUNGNEDNk+PVHlU/K4DgT ppAOs07A==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1ti8rp-00000000mzV-1Tny; Wed, 12 Feb 2025 09:17:13 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 60EB8300318; Wed, 12 Feb 2025 10:17:11 +0100 (CET) Date: Wed, 12 Feb 2025 10:17:11 +0100 From: Peter Zijlstra To: Cristian Prundeanu Cc: K Prateek Nayak , Hazem Mohamed Abuelfotoh , Ali Saidi , Benjamin Herrenschmidt , Geoff Blake , Csaba Csoma , Bjoern Doebel , Gautham Shenoy , Joseph Salisbury , Dietmar Eggemann , Ingo Molnar , Linus Torvalds , Borislav Petkov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2] [tip: sched/core] sched: Move PLACE_LAG and RUN_TO_PARITY to sysctl Message-ID: <20250212091711.GA19118@noisy.programming.kicks-ass.net> References: <20250119110410.GAZ4zcKkx5sCjD5XvH@fat_crate.local> <20250212053644.14787-1-cpru@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250212053644.14787-1-cpru@amazon.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Feb 11, 2025 at 11:36:44PM -0600, Cristian Prundeanu wrote: > Replacing CFS with the EEVDF scheduler in kernel 6.6 introduced > significant performance degradation in multiple database-oriented > workloads. This degradation manifests in all kernel versions using EEVDF, > across multiple Linux distributions, hardware architectures (x86_64, > aarm64, amd64), and CPU generations. > > Testing combinations of available scheduler features showed that the > largest improvement (short of disabling all EEVDF features) came from > disabling both PLACE_LAG and RUN_TO_PARITY. > > Moving PLACE_LAG and RUN_TO_PARITY to sysctl will allow users to override > their default values and persist them with established mechanisms. Nope -- you have knobs in debugfs, and that's where they'll stay. Esp. PLACE_LAG is super dodgy and should not get elevated to anything remotely official. Also, FYI, by keeping these emails threaded in the old thread I nearly missed them again. I'm not sure where this nonsense of keeping everything in one thread came from, but it is bloody stupid.