From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 7FF432046A1; Wed, 12 Feb 2025 09:17:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739351855; cv=none; b=sYCgAgaAPHd0CD9p9DoOBvsnYQpB357q30g32kbtZeAPqcMHZ2bOIJmIU93xyOCleJRxPqKkjtm0ZZMv0GMZ8pcuWdIuR2zm/FmGiykQPinjZG2ttFAQ2/CiseGou/g5ZtyzYRy/75g8E4fXFjFMZdFOkIpXhvr5Nd74UEdSwHk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739351855; c=relaxed/simple; bh=VaWA69jLJEbx1tzGpVWQqW68uEMrEtMTNCIwHOwPWic=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KlhsXAnhrYrCj6lgh9IV6mFRK1pz0gGb6mve9acuDTbsOnE7O95GOtNTS00xP3rFszJLyk1UBYw8zGQRSDCQOL0qq2IUlAmNM928QRTZ0f0lAecu+jayH4Jr8lBNY53xlsOmmTgqa6FDcFnfJKf2CYEfPs0s2e9lUWxo38yAXOw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=UvcHBjID; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="UvcHBjID" 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> 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=us-ascii Content-Disposition: inline In-Reply-To: <20250212053644.14787-1-cpru@amazon.com> 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.