alq666

-- set up some test data
create table t2 (event text not null, ts timestamp not null);
insert into t2 (event, ts) select case when random() < 0.5 then 'event1' else 'event2' end, now() + (random() * 60 * '1 minute'::interval)  from generate_series(1, 100);

-- earliest_time
select min(ts)
  from t2
 where event = 'event1'
  group by event;
  

alq666

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

alq666

Keybase proof

I hereby claim:

• I am alq666 on github.
• I am alq (https://keybase.io/alq) on keybase.
• I have a public key ASA8hZ_wc05wAyTuPgZEtwob5PP-YjIoR2A79kI0EBA2XAo

To claim this, I am signing this object:

alq666

Internet Scale Services Checklist

A checklist for designing and developing internet scale services, inspired by James Hamilton's 2007 paper "On Desgining and Deploying Internet-Scale Services."

• http://mvdirona.com/jrh/talksandpapers/jamesrh_lisa.pdf

Basic tenets

• Does the design expect failures to happen regularly and handle them gracefully?
• Have we kept things as simple as possible?

alq666

/^TcpExt:/ {
        for (i=2; i <= NF; i++) {
                if (match($i, /[[:digit:]]+/)) {
                        values[i] = $i
                } else {
                        keys[i] = $i
                }
        }
}

alq666

  0. pxname [LFBS]: proxy name
  1. svname [LFBS]: service name (FRONTEND for frontend, BACKEND for backend,
     any name for server/listener)
  2. qcur [..BS]: current queued requests. For the backend this reports the
     number queued without a server assigned.
  3. qmax [..BS]: max value of qcur
  4. scur [LFBS]: current sessions
  5. smax [LFBS]: max sessions
  6. slim [LFBS]: configured session limit
  7. stot [LFBS]: cumulative number of connections

alq666

#!/usr/bin/env python

"""A message modification plugin to remove credentials

   Copyright (C) 2014 by Adiscon GmbH and Peter Slavov
   Copyright (C) 2016 by Datadog

   This file is part of rsyslog.

   Licensed under the Apache License, Version 2.0 (the "License");

alq666

From 504504f2f8c13f077f09e0906cd7e7d3ca405acc Mon Sep 17 00:00:00 2001
From: Vincent Bernat <[email protected]>
Date: Wed, 7 May 2014 18:18:07 +0200
Subject: [PATCH] MINOR: dtrace: add dtrace support (WIP)

Both dtrace and systemtap are supported. Currently, only one tracepoint
is defined.
---
 .gitignore             |  1 +
 Makefile               | 18 +++++++++++++++++-

alq666

# Place a probe to record calls and return values of enqueue_to_backlog
sudo perf probe -a 'enqueue_to_backlog%return $retval'
# Record for 60 seconds
sudo perf record -e probe:enqueue_to_backlog -aR sleep 60
# Display calls
sudo perf script

alq666

/rto/ {
        # $3 rto:xxx
        # $10 unacked:x
        # $11 retrans:x/y
        # $12 lost:x
        split($3, arr, ":");
        rto = arr[2];
        if (match($0, /rto:([[:digit:]]+)/, arr)) rto = arr[1];
        if (match($0, /unacked:([[:digit:]]+)/, arr)) unacked = arr[1];
        if (match($0, /retrans:([[:digit:]]+)?\/([[:digit:]]+)/, arr)) retrans = arr[1];