VIDEOS 》 Linux Kernel Programming

Download this episode my entire kernel module sample code, make file, clean script HERE. And here is the source code for a quick reference.

/* kmalloc_vs_vmalloc 
 * The Linux Channel
 * Author: Kiran Kankipati
 * Updated: 23-nov-2016
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kiran Kankipati");
MODULE_DESCRIPTION("kmalloc vs vmalloc");
MODULE_VERSION("0.1");

unsigned char *kmallocbuf;
unsigned char *vmallocbuf;

#define BUFLEN 1000

static int __init kmalloc_vs_vmalloc_init(void)
{	unsigned long js, je, jdiff;
	int i=0,j=0;
   kmallocbuf = kmalloc( BUFLEN, GFP_KERNEL);
   if(kmallocbuf)
   {	sprintf(kmallocbuf, "This is a test (kmallocbuf)\n");
     	printk("%s", kmallocbuf);
     	
     	js = jiffies;
     	for(j=0;j<100000;j++){ for(i=0;i<BUFLEN;i++) { kmallocbuf[i] = i+j; } }
     	je = jiffies;
     	printk("dummy print kmallocbuf: %02x\n", kmallocbuf[15]);
     	jdiff = je - js;
     	printk("\nEnd Time [%lu] - Start Time [%lu] - Diff [%lu]\n",je,js, jdiff);
   }
   printk("-------------------------------\n");
   
   vmallocbuf = vmalloc(BUFLEN);
   if(vmallocbuf)
   {	sprintf(vmallocbuf, "This is a test (vmallocbuf)\n");
   	printk("%s", vmallocbuf);
   	
   	js = jiffies;
   	for(j=0;j<100000;j++){ for(i=0;i<BUFLEN;i++) { vmallocbuf[i] = i+j; } }
     	je = jiffies;
     	printk("dummy print vmallocbuf: %02x\n", vmallocbuf[15]);
     	jdiff = je - js;
     	printk("\nEnd Time [%lu] - Start Time [%lu] - Diff [%lu]\n",je,js, jdiff);
   }
   return 0;
}


static void __exit kmalloc_vs_vmalloc_exit(void)
{	
   kfree(kmallocbuf);
   vfree(vmallocbuf);
}

module_init(kmalloc_vs_vmalloc_init);
module_exit(kmalloc_vs_vmalloc_exit);

Suggested Topics:

Video Episodes :: Linux Kernel programming

Linux Kernel /sysfs Interface ↗
Saturday' 14-May-2022

/sysfs is one of the most popular kernel to user-space interface which you can leverage to add an interface to your Kernel code such as Kernel modules, Kernel Device Drivers, etc. Although personally I prefer /proc interface than other alternatives such as /sysfs, ioctl() and so on for my personal Kernel modules/stack. So here is my detailed multi-episode Youtube video series on /sysfs Interface.

Linux Operating System - User-space Processes ↗
Thursday' 19-Oct-2023

Linux Kernel vs User-space - Library APIs - Linux Kernel Programming ↗
Friday' 27-Oct-2023

One of the important aspects a beginner who is into Linux Kernel space systems software development has to understand is that unlike user-space C/C++ programming, where you can freely include any library APIs via respective #include files (which are dynamically linked during run-time via those /lib .so files), in the case of Kernel space programming, these library APIs are written within the Kernel source itself. These are the fundamental APIs which we commonly use, such as memcpy(), memcmp(), strlen(), strcpy(), strcpy() and so on. So here is my detailed Youtube video episode on the same with live demo, walk-through and examples.

Linux Kernel Compilation ↗
Thursday' 19-Oct-2023

Linux Kernel Programming ↗
Saturday' 13-Mar-2021

Linux Kernel Programming - Device Drivers ↗
Saturday' 13-Mar-2021

Watch detailed videos and read topics on Linux Kernel Programming - Device Drivers

What is purpose of Kernel Development - Example SMOAD Networks SDWAN Orchestrator Firewall Kernel Engine ↗
Monday' 18-Jul-2022

Often aspiring students may have this question, that what is the purpose of Linux Kernel Development. Since Linux Kernel is very mature and it has almost everything one would need. Usually, we need custom kernel development in the case of any new driver development for new upcoming hardware. And this happens on and on. But at times we may also come across few features/modules/components which are already provided by the Linux Kernel which are not adequate or atleast not the way we exactly intended to use. So, this is the real-world example, sometimes no matter what Linux Kernel provides as a part of stock Kernel/OS features, sometimes we have to write our own custom kernel stack or module(s) which can specifically cater our exact needs.

Linux Kernel Architecture ↗
Wednesday' 18-May-2022

Linux Kernel /proc Interface ↗
Thursday' 19-Oct-2023

/proc is one of the most popular kernel to user-space interface which you can leverage to add an interface to your Kernel code such as Kernel modules, Kernel Device Drivers, etc. Personally I prefer /proc interface than other alternatives such as /sysfs, ioctl() and so on for my personal Kernel modules/stack. So here is my detailed multi-episode Youtube video series on /sysfs Interface. I also conduct sessions/classes on Systems and Network software programming and architecture.

Linux Kernel - Containers and Namespaces ↗
Saturday' 13-Mar-2021

Linux Kernel FileSystems Subsystem ↗
Sunday' 29-Oct-2023

Linux ioctl() API interface ↗
Saturday' 13-Mar-2021

Watch detailed videos and read topics on Linux Kernel Programming and Linux ioctl() API interface