In a post a few months back I said it’s a popular myth that const is helpful for enabling compiler optimisations in C and C++ . I figured I should explain that one, especially because I used to believe it was obviously true, myself. I’ll start off with some theory and artificial examples, then I’ll do some experiments…
From the operating system's point of view, we have a large pool of memory from some starting address to some ending address. We can use our linker script (the virt.lds file) to provide us symbols representing the address of the starting and ending points.
In this regularly but rarely updated article, which is without doubt the most comprehensive list of Linux distributions' problems on the entire Internet, we only discuss their main problems and shortcomings (which may be the reason why some people say Linux distros are not ready for the desktop) while everyone should…
I’m working on more posts about the Catalina release, but I wanted to start with a short warning. I’ve heard a bunch of reports of data loss in Apple Mail. Thankfully, none seem to be caused by my apps . (Ironically, one of the bugs I’ve encountered is the inability to delete messages via AppleScript.) And, in fact…
Killing processes in a Unix-like system can be trickier than expected. Last week I was debugging an odd issue related to job stopping on Semaphore. More specifically, an issue related to the killing of a running process in a job.
xxh3 XXH3 - a new speed-optimized hash algorithm The xxHash family of hash functions has proven more successful than ...
Complete Guide on understanding the Syslog protocol, syslog message format as well as log forwarding. Best practices included!
More or less anyone using modern PCs has to wonder: Why does Windows use backslash as a path separator when the rest of the world uses forward slash? The clear intermediate answer is “because DOS and OS/2 used backslash”. Both Windows 9x and NT were directly or indirectly derived from DOS and OS/2, and certainly…
ps aux | more
Compiling a CPU, in a cheap FPGA board
File systems unfit as distributed storage backends: lessons from 10 years of Ceph evolution Aghayev et al., SOSP’19 Ten years of hard-won lessons packed into just 17 pages (13 if you don’t co…
I often see code where authors abstract away details by placing them in some external function. Here is a toy example:
BPF Performance Tools: Linux System and Application Observability (book)
For some time Elfeed was experiencing a strange, spurious failure. Every so often users were seeing an error (spoiler warning) when updating feeds: “error in process sentinel: Search failed.” If you use Elfeed, you might have even seen this yourself. From the surface it appeared that curl, tasked with the…
A laundry list of speed limits that your code can’t exceed.
You're probably reading this page because you've attempted to access some part of my blog (Wandering Thoughts) or CSpace , the wiki thing it's part of. Unfortunately you're using a browser version that my anti-crawler precautions consider suspicious, most often because it's too old (most often this applies to versions…
Verilog is the de facto abstraction for programming today’s FPGAs. RTL programming is fine if you want to use FPGAs for their traditional purpose as circuit emulators, but it’s not the right thing for the new view of FPGAs as general-purpose computational accelerators.
Take manual control of your Linux system’s DNS resolution and keep programs from interfering with and overwriting your resolv.conf file.
A vision of an OS that recognizes that any user activity and most of the system activities are nothing but queries, which ought to be treated uniformly and implemented efficiently once and for all; database as a file system; A paper submitted to MacHack'95
Good judgement is the result of experience ... Experience is the result of bad judgement. — Fred Brooks
An overview of the PureDarwin project, which is a community effort to produce a more usable version of Darwin OS, the open source base behind modern Mac OS.
While working on our Spectrum server , we noticed something weird: the TCP sockets which we thought should have been closed were lingering around. We realized we don't really understand when TCP sockets are supposed to time out!
Almost every one of you must have written a program, compiled it and then ran it to see the fruits of your hard labour. It feels good to finally see your program working, isn’t it? But to make all of this work, we have someone else to thankful too. And that is your compiler (of course, assuming that you are working in…
This is a psuedo-transcript for a talk given at Deconstruct 2019. To make this accessible for people on slow connections as well as people using screen readers, the slides have been replaced by in-line text (the talk has ~120 slides; at an average of 20 kB per slide, that's 2.4 MB. If you think that's trivial…
I’ve previously blogged about using Pi Zero (and Zero W) devices as USB Gadgets. This allows them to be powered and accessed via one of the micro USB sockets and it shows up as both a CD-Driv…
