From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 140F42063F4; Wed, 12 Feb 2025 09:43:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739353399; cv=none; b=GvXwYBsAo2a8dNuzO++wtM7TuuESqZwf+py67TdhM/8GNxCe/754TCypzg5eCbFbD9EuaXY+jF2lehyp9WUvOJiRpeXLb43F71J/SrGQXrevT3U71TLz/1KDaG5qSpzdU41hyopkXunVnpvG08jtn4fT9lI3lNDeCmymPWv9mE8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739353399; c=relaxed/simple; bh=riQIaA9jfwloeLuUC0rqMjOvmr9G0HwhV6cOCq/AckM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZdyyBcQot6MWrZ+3VeY0NrFoPg5E1/KGmd8hIJFPji9Hl/iApB7nfprPY3jyw21r2pMgPQ1ku1VLEhTadJottZrOH/v9+4kFPzoc3aHkBaYRSt0tiayhGZrls9NGxsXAngq/8BGiaTYAKAue6Ik/3Ihq9Y++wVwCKr5n0zo0sSU= 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=ZKUNfn9Y; arc=none smtp.client-ip=90.155.50.34 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="ZKUNfn9Y" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=dTFlbsmC0WjAMz9CQYs4K20vlagORcevhwzqv7FeHjg=; b=ZKUNfn9YKrc+sODKhuuCqPIHU/ EUk+PNBuuNAGWpkntmcAJcn9aEay6YbmY3I3dW/oNrdv7DjEpodbkwIvrEXh5r7y9pqgb5AO6RNmp 60UY/sNaibBFCkJUkwnZJQmUTee0nsaoWuiWucVdQq7oXBml+IrBw+JdPo7HKwBT/4qrjyju8wUIz A+nZ3rsg7cfauDLma5ZrHC04J5p53wP86aZyxzy2rHyy4/f4Umoc/0iY6Sqz77Uj+xjwtUG7UeZxx bwtUJxO+uE8P+G+WUjuzSt4bR8Z+MzVJKr4mJL90r9FYWDgWZrVEFWs9fSny+N2u9rrJIVeV/sFZC XAbFSFdg==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1ti9Gu-00000004Al6-1Win; Wed, 12 Feb 2025 09:43:08 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id F2CDF300318; Wed, 12 Feb 2025 10:43:07 +0100 (CET) Date: Wed, 12 Feb 2025 10:43:07 +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 0/2] [tip: sched/core] sched: Disable PLACE_LAG and RUN_TO_PARITY and move them to sysctl Message-ID: <20250212094307.GB19118@noisy.programming.kicks-ass.net> References: <20250119110410.GAZ4zcKkx5sCjD5XvH@fat_crate.local> <20250212054113.19938-1-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: <20250212054113.19938-1-cpru@amazon.com> On Tue, Feb 11, 2025 at 11:41:13PM -0600, Cristian Prundeanu wrote: > Your find also helps to point out that even when it works, SCHED_BATCH is > a more complex and error prone mitigation than just disabling PL and RTP. > The same reproducer setup that uses systemd to set SCHED_BATCH does show > improvement in 6.12, but not in 6.13+. There may not even be a single > approach that works well on both. > > Conversely, setting NO_PLACE_LAG + NO_RUN_TO_PARITY is simply done at boot > time, and does not require further user effort. For your workload. It will wreck other workloads. Yes, SCHED_BATCH might be more fiddly, but it allows for composition. You can run multiple workloads together and they all behave. Maybe the right thing here is to get mysql patched; so that it will request BATCH itself for the threads that need it.