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diff --git a/reference/C/LIBRARIES/syscalls.htm b/reference/C/LIBRARIES/syscalls.htm new file mode 100644 index 0000000..e74dd70 --- /dev/null +++ b/reference/C/LIBRARIES/syscalls.htm @@ -0,0 +1,61 @@ +<html> +<head> +<title>System calls and library calls</title> +<script language="JavaScript"> +</script> +</head> + +<body bgcolor="#ffffcc"> +<hr> +<center> +<h1>System calls and library calls</h1> +</center> +<hr> +<p> + +I have wondered for sometime what the difference is between +system calls (found in section 2 of the man pages) +and library calls (in section 3). + +Its simple... + +<ul> +<li>system calls are provided by the <i>system</i> +and are executed in the system kernel. They are entry points +into the kernel and are therefore NOT linked into your +program. These are not portable +calls. +<li>Library calls include the ANSI C standard library and are +therefore portable. These functions are linked into your program. +</ul> + +It is worth noting that, because system calls are part of the +O/S. The program has to make a context switch to the kernel +when they are called and because of this, they have a high +startup overhead. The upside is that the time executing these +routines is assigned to the OS and not the user program. + +<p> +<hr> +<p> +<center> +<table border=2 width="80%" bgcolor="ivory"> +<tr align=center> +<td width="25%"> +<a href="../cref.html"> Top</a> +</td><td width="25%"> +<a href="../master_index.html"> Master Index</a> +</td><td width="25%"> +<a href="../SYNTAX/keywords.html"> Keywords</a> +</td><td width="25%"> +<a href="../FUNCTIONS/funcref.htm"> Functions</a> +</td> +</tr> +</table> +</center> +<p> +<hr> +<address>Martin Leslie +</address><p> +</body> +</html> |