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Tag: linux
How to see the sum of all context switches of all threads within a Java process?
I am running pidstat on CentOS linux to monitor a Java application. When I feed the java pid to pidstat it never shows any context switches. I have to find the pid of a specific Java thread (using top -H) to see the context switches. How can you see the sum of all context switches of all threads within a
How to install latest version of git on CentOS 8.x/7.x/6.x
I used the usual: It did not install the latest version of git on my CentOS 6. How can I update to the latest version of git for CentOS 6? The solution can be applicable to newer versions of CentOS such as CentOS 7. Answer You can use WANDisco’s CentOS repository to install Git 2.x: for CentOS 6, for Ce…
Initialization of number of free pages in each order in a memory zone
I am going through the memory initialization code in linux kernel, and I can see the number of free pages for each order and migration type for the each memory zone in a memory node is set to 0. I am not able to figure out how the list is set to the proper state, as in which order has
What does “high involuntary context” switches mean?
I have re-written a part of code in C. When testing it with logging the resource usage using getrusage(2) C API. Before changing the code: After changing: I see a lot of involuntary context switches being done in the code I have re-written. My question is not about how to reduce context switches. But.. What h…
iptables LOG and DROP in one rule
I am trying to log outgoing connections with iptables. What I want is, drop and accept connection while logging them also. I have found that -j option takes DROP/REJECT/ACCEPT/LOG. But I want to do something like DROP and LOG or ACCEPT and LOG. Is there a way to achieve this ? Answer Example: Log Exampe: Othe…
Understanding load average vs. cpu usage [closed]
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Adding additional newline between each line
I am analyzing log files from my server(particular few lines from there). But those lines are having around 1000 to 2000 characters in length. Here is an example how the lines are coming out with grep and less with following command. Output: But its hard for me to separate them as those are screen full of tex…
I do not understand how execlp() works in Linux
I have spent the last 2 days trying to understand the execlp() system call, but yet here I am. Let me get straight to the issue. The man page of execlp declares the system call as int execlp(const char *file, const char *arg, …); with the description: The const char arg and subsequent ellipses in the ex…
Output results from Linux command into a table with PHP
I’m mid way through clobbering together a captive portal to run on a Raspberry Pi and have the basics working, but I’m now stumbling whilst creating some administration pages. What I am essentially trying to do is create a table in HTML/PHP so that I have the ability to “kick” users fr…