henrik

tmux cheatsheet

As configured in my dotfiles.

start new:

tmux

start new with session name:

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

elazarl

package cp

import (
	"io"
	"os"
)

func cp(dst, src string) error {
	s, err := os.Open(src)
	if err != nil {

jyap808

package main

import (
	"bytes"
	"code.google.com/p/go.crypto/openpgp"
	"code.google.com/p/go.crypto/openpgp/armor"
	"fmt"
	"io/ioutil"
	"log"
)

tsenart

package main

import (
	"net/http"
	"database/sql"
	"fmt"
	"log"
	"os"
)

insofaras

*************************************************************
*                      Important Note                       *
*************************************************************
*   This gist is no longer being updated with new quotes.   *
*   Please use https://dev.abaines.me.uk/quotes/ instead.   *
*************************************************************

Here are the quotes stored by insobot, in csv format, one file per channel. Times are UTC.

rygorous

Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
mysterious cases where it helps?

A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
I think it's useful to know what compiler writers are accomplishing by this.

TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
fairly common cases. The signed overflow UB exploitation is an attempt to work around this.

pervognsen

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <windows.h>
#include <stdint.h>

#define Assert(x) \
    if (!(x)) { MessageBoxA(0, #x, "Assertion Failure", MB_OK); __debugbreak(); }

enum Register {
    RAX = 0,

nlguillemot

In order to effectively use a multi-core CPU, a decomposition of code into tasks must be made. By decomposing code into tasks, the tasks can be distributed among CPU cores by a scheduler. Tasks can have dependencies on other tasks, meaning that the tasks execute in a partial order. This partial order can be represented as a graph, where each task has predecessors and successors. A task can only execute when all its predecessors have completed.

To implement this, we can explicitly create a graph of tasks, with edges between tasks to identify predecessor/successor relationships. The problem with a general task graph system is that it's not productive to work with. Maybe it's okay for some purposes to have a GUI interface to build a task graph, but that's too tedious for everyday code. Imagine if you had to explicitly create nodes and edges when implementing a single-threaded function call graph, it would be so tedious!

Brainiarc7

Tuning Intel Skylake and beyond for optimal performance and feature level support on Linux:

Note that on Skylake, Kabylake (and the now cancelled "Broxton") SKUs, functionality such as power saving, GPU scheduling and HDMI audio have been moved onto binary-only firmware, and as such, the GuC and the HuC blobs must be loaded at run-time to access this functionality.

Enabling GuC and HuC on Skylake and above requires a few extra parameters be passed to the kernel before boot.

Instructions provided for both Fedora and Ubuntu (including Debian):

Note that the firmware for these GPUs is often packaged by your distributor, and as such, you can confirm the firmware blob's availability by running: