This is progconc/syscall_speed.c, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it is a supplementary file for Chapter 3.

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.


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  Cover of The Linux Programming Interface

Function list (Bold in this list means a function is not static)

/* syscall_speed.c

   By repeatedly invoking a simple system call (getppid()), we can get some
   idea of the cost of making system calls.

   Usage: time syscall_speed numcalls

   Compiling with -DNOSYSCALL causes a call to a simple function
   returning an integer, which can be used to compare the overhead
   of a simple function call against that of a system call.
#include "tlpi_hdr.h"

static int myfunc() { return 1; }
main(int argc, char *argv[])
    int numCalls = (argc > 1) ? getInt(argv[1], GN_GT_0, "num-calls")
                              : 10000000;

        printf("Calling normal function\n");
        printf("Calling getppid()\n");

    for (int j = 0; j < numCalls; j++)



Download progconc/syscall_speed.c

Note that, in most cases, the programs rendered in these web pages are not free standing: you'll typically also need a few other source files (mostly in the lib/ subdirectory) as well. Generally, it's easier to just download the entire source tarball and build the programs with make(1). By hovering your mouse over the various hyperlinked include files and function calls above, you can see which other source files this file depends on.

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