svn commit: r46547 - head/en_US.ISO8859-1/htdocs/news/status

Tue Apr 14 23:31:30 UTC 2015

Author: bjk
Date: Tue Apr 14 23:31:28 2015
New Revision: 46547
URL: https://svnweb.freebsd.org/changeset/doc/46547

Log:
  Add report on nanosecond file timestamps
  
  Approved by:	hrs (mentor, implicit)

Modified:
  head/en_US.ISO8859-1/htdocs/news/status/report-2015-01-2015-03.xml

Modified: head/en_US.ISO8859-1/htdocs/news/status/report-2015-01-2015-03.xml
==============================================================================

--- head/en_US.ISO8859-1/htdocs/news/status/report-2015-01-2015-03.xml	Tue Apr 14 23:26:24 2015	(r46546)
+++ head/en_US.ISO8859-1/htdocs/news/status/report-2015-01-2015-03.xml	Tue Apr 14 23:31:28 2015	(r46547)
@@ -1475,4 +1475,56 @@ WITHOUT_FORTH=y</pre>
       </task>
     </help>
   </project>
+
+  <project cat='kern'>
+    <title>Nanosecond file timestamps</title>
+
+    <contact>
+      <person>
+	<name>
+	  <given>Jilles</given>
+	  <common>Tjoelker</common>
+	</name>
+	<email>jilles at FreeBSD.org</email>
+      </person>
+
+      <person>
+	<name>
+	  <given>Sergey</given>
+	  <common>Kandaurov</common>
+	</name>
+	<email>pluknet at FreeBSD.org</email>
+      </person>
+    </contact>
+
+    <body>
+      <p>Two new system calls, futimens() and utimensat(), were
+	added, making it possible to set file timestamps with nanosecond
+	accuracy.  Various utilities like cp, mv and touch were changed
+	to use the new calls to preserve and set timestamps with
+	full precision.</p>
+
+      <p>The stat() and related system calls have returned file
+	timestamps with nanosecond accuracy for a long time, but there
+	was no way to set a timestamp more accurately than
+	microseconds.</p>
+
+      <p>With these changes, it will be possible to use more
+	accurate timestamps (sysctl vfs.timestamp_precision=3) without
+	anomalies such as a copy of a file (from cp -p) appearing older
+	than the original.  This is particularly useful for NFS servers,
+	which use file timestamps for cache invalidation.</p>
+    </body>
+
+    <help>
+      <task>
+	<p>Where possible, fix code that still sets inaccurate
+	  timestamps on files, typically by calling futimes(),
+	  futimesat(), lutimes(), utime() or utimes() with a non-null
+	  times pointer.  There may be a reason for this such as a limited
+	  network protocol or file format, but there is some code left
+	  that can be fixed.</p>
+      </task>
+    </help>
+  </project>
 </report>
