From owner-svn-src-stable@freebsd.org Mon Jan 23 18:12:22 2017 Return-Path: Delivered-To: svn-src-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 87E7FCBE43D; Mon, 23 Jan 2017 18:12:22 +0000 (UTC) (envelope-from vangyzen@FreeBSD.org) Received: from smtp.vangyzen.net (hotblack.vangyzen.net [199.48.133.146]) by mx1.freebsd.org (Postfix) with ESMTP id 6ACA3C5F; Mon, 23 Jan 2017 18:12:21 +0000 (UTC) (envelope-from vangyzen@FreeBSD.org) Received: from sweettea.beer.town (unknown [76.164.8.130]) by smtp.vangyzen.net (Postfix) with ESMTPSA id 992655649D; Mon, 23 Jan 2017 12:12:15 -0600 (CST) Subject: Re: svn commit: r312666 - stable/10/sys/kern To: Andriy Gapon , Bruce Evans References: <201701230834.v0N8Ypnu011042@repo.freebsd.org> <20170124002712.Q903@besplex.bde.org> <49838a2b-c628-da8c-4c9c-4a66c83119f8@FreeBSD.org> Cc: src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-stable@FreeBSD.org, svn-src-stable-10@FreeBSD.org From: Eric van Gyzen Message-ID: Date: Mon, 23 Jan 2017 12:12:14 -0600 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101 Thunderbird/45.5.0 MIME-Version: 1.0 In-Reply-To: <49838a2b-c628-da8c-4c9c-4a66c83119f8@FreeBSD.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-BeenThere: svn-src-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for all the -stable branches of the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Jan 2017 18:12:22 -0000 On 01/23/2017 10:03, Andriy Gapon wrote: > On 23/01/2017 15:34, Bruce Evans wrote: >> What is a good benchmark for showing that the fix helps? > > Honestly, I do not know. We ran into a pathology where a thread was not getting > scheduled for a long time after being preempted while in a critical section (so > the actual preemption was a voluntary switch when exiting the critical section). > I am not sure what kind of a synthetic benchmark or a test case would readily > demonstrate the problem. I submitted r270423, which introduced the bug Andriy just fixed. I'm already setting up the performance test that I used for that change. It's a macro-benchmark of a commercial product, so I can't elaborate on details, but at least I can give a thumb indication in the style of a Roman Dictator. Eric