svn commit: r48679 - head/en_US.ISO8859-1/htdocs/news/status

Wed Apr 20 01:10:09 UTC 2016

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 <imp at bsdimp.com>.

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 @@
 	<a href="https://www.freebsdfoundation.org/blog/introducing-a-new-look-for-the-foundation/">new look</a>.</p>
     </body>
   </project>
+
+  <project cat='kern'>
+    <title>CAM I/O Scheduler</title>
+
+    <contact>
+      <person>
+	<name>
+	  <given>Warner</given>
+	  <common>Losh</common>
+	</name>
+	<email>wlosh at netflix.com</email>
+      </person>
+    </contact>
+
+    <links>
+      <url href="https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf">I/O Scheduling in FreeBSD's CAM Subsystem (PDF)</url>
+      <url href="https://www.youtube.com/watch?v=3WqOLolj5EU">The BSDCan 2015 Talk</url>
+    </links>
+
+    <body>
+      <p>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
+	<a href="https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf">I/O Scheduling in FreeBSD's CAM Subsystem article (PDF)</a>
+	or from
+	<a href="https://www.youtube.com/watch?v=3WqOLolj5EU">the BSDCan 2015 talk</a>.</p>
+
+      <p>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.</p>
+    </body>
+
+    <sponsor>Netflix</sponsor>
+  </project>
 </report>
