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 3344C1D88A4; Thu, 17 Oct 2024 09:10:45 +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=1729156248; cv=none; b=SOUnIkwqXlogEwp4rQ36+gd/j0AfvMDd5iTIm1KclD2mJ8Quaeox9RfbCqxdtdnDkMX9TfWbUxf80ryVRts4yaBfLS6tZG1Xk+fL3yTfeKORdtOKhkhlBYQaGOlJmngfDKOlLpDY9Z1x+OJQ/hNdzl++7/NycjTI1Y+EZyZcnlc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729156248; c=relaxed/simple; bh=vkUdPO+YIv6UsgWnupr1JbvuHq5pN/V19qg0DmTGilY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=t6iOna4IketU0lRqikydrHI198CAPtckhrKu7Lw4P3w6rG8bMTkYTyX3HY6axk6KGz0Bv/Ux6iHuyWxrw0QQj7q91Xt8r7iU8I98/3+ikGD0P009B+o2m9Q38xVLBk5LvYmtAvDg6/7ELum1W5sDnmZKkBCADEDw9JrDhWaRs+E= 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=bsPsW6+W; 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="bsPsW6+W" 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=93T41rkeDd78b9KfSigfA60vyErE/d0x4myn52H8IsQ=; b=bsPsW6+WGCYP5M4+yngNqGJPSF nhKuJlJXlsw+v8fRY0BZfLQtlw8pDt7EFuP6b0w+YO9a9qc2TcZfG0T0pGXNwt/3/9ELb+rqBSvY4 Wtv23BEw2JGsHV7DWJqSjl608roQ0kKjuyCCzO5z7mqr9PX/G2vVyqgUOgae82875EQ5na2fMee7c 7QrbT1MtEF1GAWhaot5Ttb+UPK2lpaNwaFQ9b/9HC+LrlP+pTzvjaKAgW/O7O4rRIsQeZsVn02kZo R5Wsu3WN0ov0GK5+E/mkSFtWFJCzMrP2RNEHBG1uxVbF+OyuY4WI5uxOq3EFdMG2DKY8Y18M1P5xw 9KQhWH6Q==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t1MWj-000000075cM-0S7F; Thu, 17 Oct 2024 09:10:37 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 5BD613005AF; Thu, 17 Oct 2024 11:10:36 +0200 (CEST) Date: Thu, 17 Oct 2024 11:10:36 +0200 From: Peter Zijlstra To: Cristian Prundeanu Cc: linux-tip-commits@vger.kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar , x86@kernel.org, linux-arm-kernel@lists.infradead.org, Bjoern Doebel , Hazem Mohamed Abuelfotoh , Geoff Blake , Ali Saidi , Csaba Csoma , gautham.shenoy@amd.com Subject: Re: [PATCH 0/2] [tip: sched/core] sched: Disable PLACE_LAG and RUN_TO_PARITY and move them to sysctl Message-ID: <20241017091036.GT16066@noisy.programming.kicks-ass.net> References: <20241017052000.99200-1-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: <20241017052000.99200-1-cpru@amazon.com> On Thu, Oct 17, 2024 at 12:19:58AM -0500, Cristian Prundeanu wrote: > For example, running mysql+hammerdb results in a 12-17% throughput Gautham, is this a benchmark you're running? > 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: How does using SCHED_BATCH compare? > While the long term approach is debugging and fixing the scheduler > behavior, algorithm changes to address performance issues of this nature > are specialized (and likely prolonged or open-ended) research. Until a > change is identified which fixes the performance degradation, in the > interest of a better out-of-the-box performance: (1) disable these > features by default, and (2) expose these values in sysctl instead of > debugfs, so they can be more easily persisted across reboots. So disabling them by default will undoubtedly affect a ton of other workloads. And sysctl is arguably more of an ABI than debugfs, which doesn't really sound suitable for workaround. And I don't see how adding a line to /etc/rc.local is harder than adding a line to /etc/sysctl.conf