From eb723f3af910be32f6de36d2417f816eda8d5618 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Fri, 1 Jan 2016 09:10:21 -0600
Subject: [PATCH] Update time command description in the NSH document

---
 Documentation/NuttShell.html | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/NuttShell.html b/Documentation/NuttShell.html
index 3e64ca0588b..cb0c5b02f74 100644
--- a/Documentation/NuttShell.html
+++ b/Documentation/NuttShell.html
@@ -2642,7 +2642,7 @@ time &quot;&lt;command&gt;&quot;
   Perform command timing.
   This command will execute the following &lt;command&gt; string and then show how much time was required to execute the command.
   Time is shown with a resolution of 100 microseconds which may be beyond the resolution of many configurations.
-  Note that the &lt;command&gt; string must be enclosed in quotation marks.
+  Note that the &lt;command&gt; must be enclosed in quotation marks if it contains spaces or other delimiters.
 </p>
 <p><b>Example:</b></p>
 <ul><pre>
@@ -2654,7 +2654,13 @@ nsh&gt;
 <p>
   The additional 10 millseconds in this example is due to the way that the sleep command works: It always waits one system clock tick longer than requested and this test setup used a 10 millisecond periodic system
   timer.
-  Sources of error could include the additional overhead of the time command execution itself which is included in the total and various quantization errors.
+  Sources of error could include various quantization errors, competing CPU usage, and the additional overhead of the time command execution itself which is included in the total.
+</p>
+<p>
+  The reported time is the elapsed time from starting of the command to completion of the command.
+  This elapsed time may not necessarily the processing time for the command.
+  In a busy system, command processing could be delayed if pre-empted by other, higher priority threads competing for CPU time.
+  So the reported time includes all CPU processing from the start of the command to its finish possibly including unrelated processing time during that interval.
 </p>
 <p>
   Notice that: