I’ve known for a long time that if you delete a file on Unix / Linux but that file is open somewhere, the blocks used by the file aren’t freed until that user closes the file (or is terminated), but I was left wondering about some other edge cases. Shaken Fist has a distributed blob…
Category: Linux
Linux bridges have their MTU overwritten when you add an interface
I discovered last night that network bridges on linux have their Maximum Transmission Unit (MTU) overwritten by whatever is the MTU value of the most recent interface added to the bridge. This is bad. Very bad. Specifically this is bad because MTU matters for accurately describing the capabilities of the network path the packets will…
The KSM and I
I spent much of yesterday playing with KSM (Kernel Shared Memory, or Kernel Samepage Merging depending on which universe you come from). Unix kernels store memory in “pages” which are moved in and out of memory as a single block. On most Linux architectures pages are 4,096 bytes long. KSM is a Linux Kernel feature…
The last week for linux.conf.au 2019 proposals!
Dear humans of the Internet — there is ONE WEEK LEFT to propose talks for linux.conf.au 2019. LCA is one of the world’s best open source conferences, and we’d love to hear you speak! Unsure what to propose? Not sure if your talk is what the conference would normally take? Just want a chat?…
Giving serial devices meaningful names
This is a hack I’ve been using for ages, but I thought it deserved a write up. I have USB serial devices. Lots of them. I use them for home automation things, as well as for talking to devices such as the console ports on switches and so forth. For the permanently installed serial devices…