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Update README

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Gregory Nutt 2016-01-01 09:09:34 -06:00
parent 949b4bd520
commit 31629ee982
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nshlib/README.txt
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@ -1005,8 +1005,9 @@ o time "<command>"
Perform command timing. This command will execute the following <command>
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 <command> string
must be enclosed in quotation marks.
the resolution of many configurations. Note that the <command> must be
enclosed in quotation marks if it contains spaces or other
delimiters.
Example:
@ -1018,9 +1019,17 @@ o time "<command>"
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.
timer. 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.
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.
Notice that: