How to reload udev rules

If you made changes in udev rules, you might want to reboot to apply the changes. But, there’s a simpler method than system reboot. It depends which version you are using. I’ll put RHEL5 and RHEL6 commands which might cover most scenario. In RHEL5 $ yum install udev $ udevcontrol reload_rules $ /sbin/start_udev $ udevtriggerContinue reading “How to reload udev rules”

How to keep record the commands executed by root

If you want to keep record of the commands executed by root account, you can achieve that by using audit rules. First, add the below line in /etc/audit/audit.rules -a entry,always -S execve -F uid=0 http://pagead2.googlesyndication.com/pagead/show_ads.js And restart auditd to apply the changes $ chkconfig auditd on $ service auditd restart

How to check which applications are using hugepages

You can find how much is allocated and how much is actually used by HugePages by run the following command. $ grep -i huge /proc/meminfo AnonHugePages: 776192 kB HugePages_Total: 241 HugePages_Free: 113 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB But, there’s a time you also want to know which applications are actually used HugePages. YouContinue reading “How to check which applications are using hugepages”

How many threads are in the system

If you want to check how many threads are in the system to compare it with the maximum allowed threads by the system (kernel.threads-max), you can use one of the below two methods. $ cat /proc/loadavg 0.74 0.93 1.04 3/393 31977 4th column in the above output is related to the current threads number. InContinue reading “How many threads are in the system”