+<h2>Using "assume unchanged" bit</h2>\r
+<div class="sectionbody">\r
+<p>Many operations in git depend on your filesystem to have an\r
+efficient <tt>lstat(2)</tt> implementation, so that <tt>st_mtime</tt>\r
+information for working tree files can be cheaply checked to see\r
+if the file contents have changed from the version recorded in\r
+the index file. Unfortunately, some filesystems have\r
+inefficient <tt>lstat(2)</tt>. If your filesystem is one of them, you\r
+can set "assume unchanged" bit to paths you have not changed to\r
+cause git not to do this check. Note that setting this bit on a\r
+path does not mean git will check the contents of the file to\r
+see if it has changed — it makes git to omit any checking and\r
+assume it has <strong>not</strong> changed. When you make changes to working\r
+tree files, you have to explicitly tell git about it by dropping\r
+"assume unchanged" bit, either before or after you modify them.</p>\r
+<p>In order to set "assume unchanged" bit, use <tt>--assume-unchanged</tt>\r
+option. To unset, use <tt>--no-assume-unchanged</tt>.</p>\r
+<p>The command looks at <tt>core.ignorestat</tt> configuration variable. When\r
+this is true, paths updated with <tt>git-update-index paths…</tt> and\r
+paths updated with other git commands that update both index and\r
+working tree (e.g. <tt>git-apply --index</tt>, <tt>git-checkout-index -u</tt>,\r
+and <tt>git-read-tree -u</tt>) are automatically marked as "assume\r
+unchanged". Note that "assume unchanged" bit is <strong>not</strong> set if\r
+<tt>git-update-index --refresh</tt> finds the working tree file matches\r
+the index (use <tt>git-update-index --really-refresh</tt> if you want\r
+to mark them as "assume unchanged").</p>\r
+</div>\r