From owner-svn-doc-head@freebsd.org Wed Apr 20 01:10:09 2016 Return-Path: Delivered-To: svn-doc-head@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 06CEFB1456B; Wed, 20 Apr 2016 01:10:09 +0000 (UTC) (envelope-from wblock@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id B358C1E74; Wed, 20 Apr 2016 01:10:08 +0000 (UTC) (envelope-from wblock@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id u3K1A7Hb022161; Wed, 20 Apr 2016 01:10:07 GMT (envelope-from wblock@FreeBSD.org) Received: (from wblock@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id u3K1A7Ve022160; Wed, 20 Apr 2016 01:10:07 GMT (envelope-from wblock@FreeBSD.org) Message-Id: <201604200110.u3K1A7Ve022160@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: wblock set sender to wblock@FreeBSD.org using -f From: Warren Block Date: Wed, 20 Apr 2016 01:10:07 +0000 (UTC) To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r48679 - head/en_US.ISO8859-1/htdocs/news/status X-SVN-Group: doc-head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-doc-head@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: SVN commit messages for the doc tree for head List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Apr 2016 01:10:09 -0000 Author: wblock Date: Wed Apr 20 01:10:07 2016 New Revision: 48679 URL: https://svnweb.freebsd.org/changeset/doc/48679 Log: Add CAM I/O Scheduler report from Warner Losh . Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2016-01-2016-03.xml Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2016-01-2016-03.xml ============================================================================== --- head/en_US.ISO8859-1/htdocs/news/status/report-2016-01-2016-03.xml Tue Apr 19 18:25:50 2016 (r48678) +++ head/en_US.ISO8859-1/htdocs/news/status/report-2016-01-2016-03.xml Wed Apr 20 01:10:07 2016 (r48679) @@ -2523,4 +2523,47 @@ new look.

+ + + CAM I/O Scheduler + + + + + Warner + Losh + + wlosh@netflix.com + + + + + I/O Scheduling in FreeBSD's CAM Subsystem (PDF) + The BSDCan 2015 Talk + + + +

An enhanced CAM I/O scheduler has been committed to the tree. + By default, this scheduler implements the old behavior. + However, a more adaptive scheduler can be enabled. The more + adaptive scheduler allows pacing of different types of I/O to + allow the workload-preferred I/O to experience maximum + performance. By measuring device response time at the lowest + levels, many artifacts of software queueing can be eliminated + and better performance can be achieved. In addition, Queued + Trims are now supported for SATA devices that support them. + Details about the new scheduler are available in the + I/O Scheduling in FreeBSD's CAM Subsystem article (PDF) + or from + the BSDCan 2015 talk.

+ +

In essence, this I/O scheduler allows the user to choose + improved read performance by trading off some write + performance. Or, if SSDs cannot garbage collect fast enough + to keep up with writes, to improve write performance at the + cost of some read performance.

+ + + Netflix +