Igor Nikolaev inikolaev

The counters that are the easiest to understand and the best for making ratios that are internally consistent (i.e., always fall in the range 0.0 to 1.0) are the mem_load_retired events, e.g., mem_load_retired.l1_hit and mem_load_retired.l1_miss.

These count at the instruction level, i.e., the universe of retired instructions. For example, could make a reasonable hit ratio from mem_load_retired.l1_hit / mem_inst_retired.all_loads and it will be sane (never indicate a hit rate more than 100%, for example).

That one isn't perfect though, in that it may not reflect the true costs of cache misses and the behavior of the program for at least the following reasons:

It appplies only to loads and can't catch misses imposed by stores (AFAICT there is no event that counts store misses).
It only counts loads that retire - a lot of the load activity in your process may be due to loads on a speculative path that never retire. Loads on a speculative path may bring in data that is never used, causing misses and d

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

The Best of the Best Practices (BOBP) Guide for Python

A "Best of the Best Practices" (BOBP) guide to developing in Python.

In General

Values

"Build tools for others that you want to be built for you." - Kenneth Reitz
"Simplicity is alway better than functionality." - Pieter Hintjens

	const applyTemplate = (templateElement, data) => {
	const element = templateElement.content.cloneNode(true);
	const treeWalker = document.createTreeWalker(element, NodeFilter.SHOW_ELEMENT, () => NodeFilter.FILTER_ACCEPT);

	while(treeWalker.nextNode()) {
	const node = treeWalker.currentNode;
	for(let bindAttr in node.dataset) {
	let isBindableAttr = (bindAttr.indexOf('bind_') == 0) ? true : false;
	if(isBindableAttr) {
	let dataKeyString = node.dataset[bindAttr];

	package main

	import (
	"fmt"
	"os"
	"os/exec"
	"syscall"
	)

	func main() {

	CREATE TABLE accounts(
	id serial PRIMARY KEY,
	name VARCHAR(256) NOT NULL
	);

	CREATE TABLE entries(
	id serial PRIMARY KEY,
	description VARCHAR(1024) NOT NULL,
	amount NUMERIC(20, 2) NOT NULL CHECK (amount > 0.0),
	-- Every entry is a credit to one account...

	import javax.net.ssl.SSLParameters;
	import javax.net.ssl.SSLSocket;
	import javax.net.ssl.SSLSocketFactory;
	import java.io.*;

	/** Establish a SSL connection to a host and port, writes a byte and
	* prints the response. See
	* http://confluence.atlassian.com/display/JIRA/Connecting+to+SSL+services
	*/
	public class SSLPoke {

	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