Some Assembly Required

*not the IKEA sort. Which is entirely unlike a bubble sort.

Magic Buffers and `io_uring` Registered Buffers

kdb

kdb-IPC

io_uring

There’s a really cool little mmap gadget that maps the same underlying memory region into two contiguous virtual memory address ranges. When you write past the end of the…

Shared Memory Tickerplant Log Files

kdb

serialization

tickerplant

kdb-IPC

I posted recently about making kdb+ go faster. I forgot to mention shunning TCP and using shared memory as the transport layer.

Kerberos Authentication For kdb+

kdb

kerberos

gssapi

SPNEGO

Wherever I’ve worked on kdb+ installations the approach to authentication has been that there is no authentication. Generally, everyone’s just relied on the fact that you’d…

How to beat kdb+

kdb

serialization

tickerplant

I’ve recently been pondering how to improve the performance of kdb+. For what it’s worth, I think it’s going to be really hard to beat kdb+ at its “A game”, which is…

A new Javascript IPC library for KDB

kdb

kdb-IPC

javascript

serialization

So … at “$Work” I’ve been doing quite a bit with our Dashboard product that is being used more and more to report on different aspects of the desk’s trading activities and…

Filtering Tickerplant Log Files During Replay

kdb

kdb-IPC

tickerplant

I’ve written a new C library, which you can find in my Github KDB repository which does the same kind of thing as -11!, but allows you to provide a set of table names that…

Rewriting Tickerplant Logs On-The-Fly

kdb

tickerplant

io_uring

We have an application at work that upon restarting intraday needs to replay the market-data tickerplant log file and subscribe to the live data feed. This, of course, takes…

Streaming KDB IPC Data

kdb

kdb-IPC

It used to be the case that we rewrote c.java to be more efficient. I haven’t downloaded it for ages, and have a feeling that it now uses primitive arrays under the covers…

Another vectorised bitwise-OR function for kdb+, AVX style

kdb

AVX

SSE

MSR

In my last post on a vectorised bitwise-OR function for kdb+, I wondered towards the end what the next interesting step would be — should it be the production of an…

A vectorised bitwise-OR function for kdb+

kdb

x86_64

SSE

bitwise

assembly

A long time ago I started writing some shared-library functions for kdb+ which would offer bitwise comparison of integer vector types using SSE vector registers. I came up…

Intel Performance Monitoring: Loose Ends

kdb

MSR

performance

This post is part of the series on performance monitoring with Intel MSRs on Linux:

Scripting MSR Performance Tests With kdb+: Part 2

kdb

MSR

performance

This post continues the series on performance monitoring with Intel MSRs on Linux using the batch-oriented kernel module to read and write values from and to the MSRs. The…

Scripting MSR Performance Tests with kdb+

kdb

MSR

performance

This post is part of the series on performance monitoring with Intel MSRs on Linux:

Fun With MSRs: Counting Performance Events On Intel

x86_64

MSR

performance

This post is part of the series on performance monitoring with Intel MSRs on Linux:

Intel MSR Performance Monitoring Basics

x86_64

MSR

performance

This post is part of the series on performance monitoring with Intel MSRs on Linux:

A Linux Kernel Module For Reading/Writing MSRs

kdb

x86_64

MSR

performance

This post is part of the series on performance monitoring with Intel MSRs on Linux:

Interpreting readelf -r, in this case R_X86_64_PC32

x86_64

ELF

assembly

Having just put the monster Relocations, Relocations blog-post to bed, at one point I caught myself trying to compute a relocation from the information given by readelf -r.…

Relocations, Relocations

x86_64

ELF

assembly

The man entry for elf contains the following:

The Trouble With FSUB

assembly

It’s not often you get a really nasty surprise when writing software, and even less often that the nasty surprise is lurking in the compiler (or assembler). It turns out…

A Caesar Cypher? Using SIMD? Why?

x86_64

assembly

SSE

There’s no easy answer to that. I had applied to join a group on some social networking site which was for assembly language programmers, and to check that I hadn’t got them…

AVX matrix-multiplication, or something like it

x86_64

AVX

assembly

It’s been a while since the last post, and I can confidently say that I understand one or two percent of the new (well, new to me) world of AVX instructions. There was the…

Stack Alignment

x86_64

assembly

The System V ABI “AMD64 Architecture Processor Supplement” stipulates that the stack should be aligned to a 16-byte boundary before calling a function. It provides the…

Bounded ranges, constrained or clamped values

assembly

x86_64

x86

So, given the ability to build a jump table for a range of inputs, it would be useful to transform a given input value onto one of the valid options for that table. If you…

Switch Blocks & Jump Tables

assembly

x86_64

x86

I didn’t know how jump tables were assembled prior to starting this investigation, and as anyone interested in assembly code will testify, using Google doesn’t really help…

Compare And Swap

assembly

x86_64

x86

Atomic instructions are used by the OS to provide higher-level concurrency constructs such as locks and semaphores. Probably the best known is the cmpxchg instruction, which…

The initial stack, reading process arguments (and environment variables)

assembly

x86_64

x86

I wrote a 32-bit assembly application a while ago which performed the simple task of printing out the program arguments and then the environment variables. Most people have…

Syntax Highlighting for Assembly Code

This is now completely irrelevant as I’m now running this website using Quarto, which is completely brilliant. I thought I’d leave this in the catalogue as it was my first…

Calling Java from assembler

assembly

x86_64

x86

java

Calling ASM functions from Java

assembly

x86_64

x86

java

If you’ve been inquisitive enough to read the “About” pages¹ you’ll see that my day job involves writing software in Java. To that end, I’ve put together some code which…

Hello, World!

assembly

x86_64

x86

Well, here it is, the ubiquitous “Hello, World!” example.