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How many x86 instructions are there?
It’s surprisingly hard to give a good answer (the question was raised in this article). It depends on how you count, and the details are interesting (to me anyway). To not leave you hanging: …
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The latest blog posts to take off on Hacker News. 423 posts.
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The One Second Dash
The Amazon Dash is a $5 WiFi button that summons a truck to deliver you water or other stuff. Want your Dash to do something else? The popular approach is to sniff its ARP requests. This requires that Dash connect to your network, putting you perilously close to having some DUDE delivered with your IoT mood lighting.
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Does a compiler use all x86 instructions? (2010)
On the Z80 CPU there are so few registers and instructions that you can easily know and use them all and wish there were more of them. However, half of the time it feels like the only on you really use is ld. I imagine that if ld took half the number of clock cycles, average code would run twice as fast.
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The Ethernet PAUSE frame
This is a bizarre one. It all started when the internet seemed to go out at my house. My desktop, phone, TV, everything stopped working. The usual solution at a time like this is to power cycle the modem and router. While this fixed the situation temporarily, soon after the problem returned. What made me think this…
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Mainframes as a lifestyle choice
I started working at IBM last year on mainframe compilers with the goal of making mainframes feel a little more modern. Hence, a lot of my time is spent in z/OS . The interface I use to z/OS is Unix System Services (USS, a.k.a. the command line), but if I were up for bucking the whole moderm thing, I could break out…
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Introducing the Qt Lite project – Qt for any platform, any thing, any size
Explore the Qt Blog for the latest insights on e.g. Qt Creator, your go-to source for cross-platform development tips and updates.
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Ideas for getting started in the Linux kernel
Getting new people into OSS projects is always a challenge. The Linux kernel is no different and has it’s own set of challenges. This is a follow up and expansion of some of what I talked about at Flock about contributing to the kernel.
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135M messages a second between processes in Java (2013)
Taking a lock free queue off heap and using it as an IPC mechanism to deliver 135M messages a second between processes in Java.
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Automatically closing FIN_WAIT_2 is a violation of the TCP specification
I was asked to debug another weird issue on our network. Apparently every now and then a connection going through CloudFlare would time out with 522 HTTP error.
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Zero-cost futures in Rust
One of the key gaps in Rust’s ecosystem has been a strong story for fast and productive asynchronous I/O . We have solid foundations, like the mio library, but they’re very low level: you have to wire up state machines and juggle callbacks directly.
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Why scaling and parallelism remain hard even with new tools and languages
Distributed computing and designing a system that supports modern commerce and other high-priority applications remains one of the most difficult tasks in computing. We provide expert tips.
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Notes on Distributed Systems for Young Bloods (2013)
I’ve been thinking about the lessons distributed systems engineers learn on the job. A great deal of our instruction is through scars made by mistakes made in production traffic. These scars are useful reminders, sure, but it’d be better to have more engineers with the full count of their fingers.
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Why do CPUs have multiple cache levels?
This is a reader question from “jlforrest” that seems worth answering in more detail than just a single sentence: I understand the need for a cache but I don’t understand why there are …
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A x64 OS #1: UEFI
I briefly cover what it takes to start writing a kernel which bootstraps in UEFI, as opposed to BIOS.
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Throughput vs. Latency and Lock-Free vs. Wait-Free
On the previous post we showed an excellent presentation by Cliff Click, and one of the things he mentions is that there is performance for ...
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Notes on concurrency bugs
Do concurrency bugs matter? From the literature, we know that most reported bugs in distributed systems have really simple causes and can be caught by trivial tests, even when we only look at bugs that cause really bad failures, like loss of a cluster or data corruption. The filesystem literature echos this result …
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Appending to a file from multiple processes
Suppose you have multiple processes appending output to the same file without explicit synchronization. These processes might be working in parallel on different parts of the same problem, or these might be threads blocked individually reading different external inputs. There are two concerns that come into play:
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