From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTP id EFD7F9B1 for ; Mon, 12 May 2014 23:54:44 +0000 (UTC) Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 81F9A1FA97 for ; Mon, 12 May 2014 23:54:44 +0000 (UTC) Date: Mon, 12 May 2014 16:54:35 -0700 From: Josh Triplett To: Chris Mason Message-ID: <20140512235430.GA16440@thin> References: <5370DB7B.2040706@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5370DB7B.2040706@fb.com> Cc: ksummit-discuss@lists.linuxfoundation.org Subject: Re: [Ksummit-discuss] [TOPIC] Application performance: regressions, controlling preemption List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, May 12, 2014 at 10:32:27AM -0400, Chris Mason wrote: > Hi everyone, > > We're in the middle of upgrading the tiers here from older kernels (2.6.38, > 3.2) into 3.10 and higher. > > I've been doing this upgrade game for a number of years now, with different > business cards taped to my forehead and with different target workloads. > > The result is always the same...if I'm really lucky the system isn't slower, > but usually I'm left with a steaming pile of 10-30% regressions. How automated are your benchmark workloads, how long do they take, and how consistent are they from run to run (on a system running nothing else)? What about getting them into Fengguang Wu's automated patch checker, or a similar system that checks every patch or pull rather than just full releases? If we had feedback at the time of patch submission that a specific patch made the kernel x% slower for a specific well-defined workload, that would prove much easier to act on than just a comparison of 3.x and 3.y. - Josh Triplett