About how cilium thinks about iptables and how are they using it. — About how cilium thinks about iptables and how are they using it. Audiences For people who want to understand why cilium still uses iptables and how. Cilium doesn’t like iptables I’ve been playing with cilium for a while and was impressed by how it is leveraging ebpf to build a high performance, scalable solution for…

Trying to cover what I don’t know about Linux network — Trying to cover what I don’t know about Linux network Quite often I question myself about the role of Linux kernel memory with its network components. How many of them are allocated and when ? If it’s allocated on the fly, will the other memory allocation ( like pagecache …

What I’ve learned so far about tracing — What I’ve learned so far about tracing This is a wrap up of my practical linux tracing series. You can see older posts start from here. In this final write-up, I’ll change my style a bit, to make it more straight to the point. Here are my top 10 key…

The similarity and difference in comparison with normal workload — The similarity and difference in comparison with normal workload TL;DR Same same: Tracing kernel events ( syscall, kprobe, tracepoints ) works in the same way Profiling user-space program by perf works in the same way ( Linux 4.14+ ) But different: Namespaces prevent tracing user-space events by kernel tracing infrastructure. (…

A sysadmin’s reflection on several years of practicing OKR — A sysadmin’s reflection on several years of practicing OKR Preface This is the very first ever article about management ( ? ) . I even don’t know if a goal-setting framework like Objective Key Result can be classified as a managerial stuff, but as we ( our company / team )…

How to pick the right event[s] to drill down. — How to pick the right event[s] to drill down. Preface If you’re reading this blog, most likely you’re fan of Linux tracing and BPF based tools. Given its power, it’s very tempting to jump into your new shiny tools box to troubleshoot problems. Sometimes it works, but mostly it doesn’t. In…

Notes how writeback can affect your application’s performance — TL;DR Writeback is innocent. It ensures data consistency and free up memory for other tasks. Understand it then it will pay you back. Unfortunately, sometimes writeback can be the root cause that triggers other things that may affect your very latency-sensitive application: TLB shootdown, high context-switches, stable pages write. Writeback…

I promised my team to publish a blog post within last week, to actually meet our humble target for public blog posts last quarter ( We’re… — I promised my team to publish a blog post within last week, to actually meet our humble target for public blog posts last quarter ( We’re trying to write more but are all lazy ). This should be an article to continue my tracing series or a new finding about…

Recently I had a presentation for my team about bpftrace, what i think it’s very cool. Turns out that nobody likes it. Mostly because of my… — Recently I had a presentation for my team about bpftrace, what i think it’s very cool. Turns out that nobody likes it. Mostly because of my presentation skill, i guess. Though, the biggest question was asked is why. Why do i need this thing ? It’s cool, but it takes…