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 30886D21262 for ; Thu, 17 Oct 2024 09:14:43 +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=93T41rkeDd78b9KfSigfA60vyErE/d0x4myn52H8IsQ=; b=IZlgCNHHSnxEyV65h7mLTmDn40 fUjM7JiEYR736kU6O7AQlXMZVUOMtHLjAq0rmv2F6uaSc22TpH3vuk3TlFX2rZLPzTNRYym3i6WTa 5Pw86mOMqGHpB0Q5L9bKeUHAmPlndpmXYWwxn2pSOown5Qgg0AWce2jVWKFAWvyimRK/bvmdZ04gO cSulyHKGLzlktM4Nv456RXIMJT3EF5KCNbVPIjbYDAPVW3eBWFJsbgjEEXwrtMIGXG4KNwxs+6vkP 84rbc80sjaMqVXEea2A8qmUJeHJXmVDcGWc344pCmcympsPHLjbIGAy2O5KTstIyzE/CD2dORWuSp LnD2nb2Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t1MaX-0000000EIDr-3XEY; Thu, 17 Oct 2024 09:14:33 +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 1t1MWm-0000000EHfr-311s for linux-arm-kernel@bombadil.infradead.org; Thu, 17 Oct 2024 09:10:40 +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=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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241017052000.99200-1-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 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