If you are using spinning disks (not static ram) to store your files and directories, then a useful rule of thumb is that a 7200 rpm disk spins 120 times a second, so each byte rolls by every .0083 seconds. On average, you can do no better than 4 milliseconds to fetch the byte(s) you are after in a random access. (You can get a lot of associated bytes with the same read, so data density helps in transfer time, but not at all with disk latency). With processor cycle times in the neighborhood of a nanosecond, you can execute a lot of instructions in 4 milliseconds. You could search a few thousand bytes of directory data, even using linear search, in far less time than it would take you to access that data. So don't make your directory hierarchy too deep. Each subdirectory is going to cost you at least 4 milliseconds to read. A few levels may get cached, but that's equally true of shallow hierarchies. Keep disk accesses in mind when you design your system.
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|
