chadbrewbaker

!ls
!pwd
!uname -a
!which gcc
!which clang

chadbrewbaker

• BOLT merged into llvm.
• Magic Trace for Intel CPUs.
• Zeek tool for summary of pcaps.
• SOUPER superoptimizer.
• Bartoz benchmark writeups.
• Article on PMU counters.
• Google bench performance counters.
• Branchless programming in C++.

chadbrewbaker

Guest Andrey Akinshin @andrey_akinshin

• Benchmarks shoudld have a question about a business decision in mind.
• Corner cases are routine.
• If a few samples goes from 100ms to 5 seconds then we don't need fancy methods.
• What are practically significant differences in the context of your problem?
• Avoid measurements from cold starts - unless that is what you are trying to benchmark.
• Measure of central tendency - you usually want the median not the mean.
• Median trick - take an odd number of samples to have one number in the middle.
• Efficiency of the Harrell-Davis quantile estimator
• New Arxiv paper

chadbrewbaker

EasyPerf 21 November 2021 - Bryan Cantrill

• Performance engineering is largely debuging others' code
• Denard Scaling - as transisters get smaller, power per area stays constant
• Few use cases for multiple sockets.
• Hesitant to speculate Brendan Greg's limit estimate of around 1000 cores by 2030.
• Lots of work to do on network interconnect.
• FPGAs intially oversold their benefits - need to be open source Claire Wolfe's work
• Proprietary compilers suck. Especially Electronic Design Autmoation
• KiCAD - LLVM Circuit IR Compilers and Tools - Bluespec

chadbrewbaker

{
  "$schema": "https://json-schema.org/draft/2019-09/schema",
  "$id": "https://corelight.com/software-sensor.schema.json",
  "title": "Corelight Logs",
  "description": "Definition of all of the potential logs for this installation",
  "$defs": {
    "time": {"type": "string", "pattern": "[0-9]{4}-[0-1][0-9]-[0-3][0-9]T[0-2][0-9]:[0-5][0-9]:[0-5][0-9]\\.?[0-9]{0,6}Z"},
    "port": {"type": "integer", "minimum": 0, "maximum": 65535},
    "count": {"type": "integer", "minimum": 0, "maximum": 18446744073709551615},
    "int": {"type": "integer", "minimum": -9223372036854775807, "maximum": 9223372036854775807},

chadbrewbaker

Guest @JamesReinders. website

• On device parallelism and multi-device parallelism
• OSDI 2021 Keynote on modern hardware having many chips
• Where is the parallelism in the data?
• Amdal's law - with larger data more chances for parallelism.
• Understand the data flow. What are the device limits? Registers needed, cache line size, IO buffer size, ...?
• Excited about compute kernels that auto-vectorize.
• J language dense multiply kernel
• Non Uniform Memory Access (NUMA) - pooling of virtual memory across local devices.
• Algorithms beat hardware

chadbrewbaker

Rust Structural Search and Replace

Reorder C/C++ Includes

pahole

writing an LLVM IR Pass

----- original post -----

chadbrewbaker

Guest Matt Flemming @fleming_matt - Linux Performance

• Former Linux maintiner, performance engineer at DataStax.
• Mostly investigative work on performance regressions
• P99Conf 2021
• Which CPU frequency driver is the kernel using? What is the quality of the driver? Is it properly pinning the CPU frequency?
• Bryan Cantrill talk on developing a next generation of servers with open source well tested drivers.
• What should be the default operating system page size? Answer: benchmark - it depends.
• Linux Page Cache hit ratio research by Brendann Gregg at Netflix.
• memory mapped files Beej's Guide to Unix IPC
• Advanced Configuration and Power Interface (ACPI) tables

chadbrewbaker

Chad Brewbaker - Dallas County Libertarians

• Council Bluffs voters will need twice the ballot petition signatures under the first proposed map. This is unequal and frustrates their freedom of petition-assembly.

Iowa Const. Art. I Sec. 6 Equal Protection

Iowa Const. Art. I Sec. 2 Freedom of Petition-assembly

• LSA is engaging in doublespeak - hand gerrymandering a map in purported neutrality.

chadbrewbaker

My notes using Prodfiler on a Windows 11 pro preview build.

# Open a Powershell terminal as administrator
wsl --update
wsl --shutdown
wsl
# Welcome to Ubuntu 20.04.2 LTS (GNU/Linux 5.10.43.3-microsoft-standard-WSL2 x86_64)
cd ~/