Following are steps to upgrade kernel on live web server
.

1. Check current version of kernel on web server using command uname -a, if
its 2.4 then download latest release for 2.4 please do not download 2.6
kernel.
You can download kernel from http://www.kernel.org/pub/linux/kernel/v2.6/
if its 2.4 then http://www.kernel.org/pub/linux/kernel/v2.4/, you can
check latest stable release from http://www.kernel.org

2. wget kernel in /usr/local/src
3. untar it using tar -zxvf linux-2.x-xxxx
4. cd linux-2.x-x
5. make clean
6. make mrproper
7. If kernel is 2.4 then copy current version of config file from
/boot/config-’uname-r’ as .config in /usr/local/src/linux-2.x-xx, if
kernel is 2.6 then you do not need to make .config in current directory
8. make menuconfig, select and check if all required modules are selected,
also make sure that your kernel supports multiple cpu
you can check it and select from processor type, if it displays support
for more then 2 kernel then you do not need to modify anything there.
9. save configuration and exit
10. make modules if kernel is 2.4 then need to run make dep before running
make modules
11. make modules_install
12. make
13. if 2.4 kernel then need to run make bzImage and then make install, you
can directly run make install if kernel is 2.6
15. now make sure bootloader and modify default kernel accordingly
grubby –bootloader-probe if it displays grub then edit /etc/grub.conf and
if its lilo then edit lilo.conf and make compiled kernel as default kernel
16. If your boot loader is lilo then you need to run 9one more command
/sbin/lilo which will update lilo
17. now its time to reboot server