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What Every Programmer Should Know About Memory Ulrich Drepper Red Hat, Inc. drepper@redhat.com November 21, 2007 Abstract As CPU cores become both faster and more numerous, the limiting factor for most programs is now, and will be for some time, memory access. Hardware designers have come up with ever more sophisticated memory handling and acceleration techniques–such as CPU caches–but these canno

1. Format SD card Following assumes that SD card is identified on your host machine as /dev/sd1 destroy contents of the card dd if=/dev/zero of=/dev/da1 bs=512 count=1 create MBR gpart create -s mbr da1 create FAT16 partition for U-Boot and kernel and make it active gpart add -s64m -t \!14 da1 gpart set -a active -i 1 da1 create FreeBSD partition gpart add -t freebsd da1 create FAT16 file system o

Abstract An important element in computers with multiple autonomous devices is the ability of a device to notify the CPU that it needs attention via an interrupt. The OS visible mechanics of interrupts for PCI devices is quite convoluted, especially on x86 PC systems. This paper will cover the various ways that PCI INTx interrupts have been implemented on x86 as well as the methods used by the sys

This is the home page for Victor A. Abell, lsof author and retired Associate Director of the Purdue University Computing Center. I hold an FCC Amateur Radio Extra Class license with the call sign W9RGB. My Internet electronic mail address is abe@purdue.edu. Get my GPG Public Key. Get my PGP (old) Public Key. LSOF The free, open-source, Unix administrative tool lsof (for LiSt Open Files) displays i

The theme is super rough, but I need to start dumping random FreeBSD content someplace. The blog is written using Hugo because it’s written in Go and because it produces statically compiled HTML pages. The general structure of blog is that posts like this one are random commentary, but articles are instructional. We’ll see how this goes…. I’m not sure it’s worth the effort to make something pretty

A Scalable Concurrent malloc(3) Implementation for FreeBSD Jason Evans <jasone@FreeBSD.org> Overview • What is malloc(3)? • Previous allocators • jemalloc algorithms and data structures • Benchmarks • Fragmentation • Discussion What is malloc(3) ? • C API for manual memory allocation/deallocation. • Historically: malloc(), calloc(), realloc(), free(). • More recently: posix_memalign(). • Non-stand

MySQL Database performance There are two popular SQL database benchmarks that are able to perform concurrent queries: super-smack and sysbench. Investigation of the super-smack workload shows that it performs large amounts of I/O in units of a single byte, which leads to huge numbers of context switches.  It is largely a microbenchmark of context switch performance, and for this reason it is diffi

UNIX guru at large <phk@FreeBSD.org> PGP key $Id: index.html,v 1.9 2004/10/24 19:28:06 phk Exp $ Ahhh, homepages. "You've got to have one" people told me. So I wrote one. Now after only five and a half year they start whining about me not "updating" my homepage... This is my "official" home-page, and as such rather general and not updated too often (next scheduled update is summer 2009). If you ar

Problem The FreeBSD UFS (both UFS1 and UFS2) and ZFS filesystems provides the possibility to create snapshots of live filesystems. On UFS is already best known (and can be easily used) for allowing fsck(8) to run in the background (see rc.conf variable background_fsck) and to create consistent filesystem dumps (see dump(8) option -L). In ZFS snapshots even can be used with the zfs(8) send and rece

Running Qemu on FreeBSD, as host This page has been moved to http://wiki.freebsd.org/qemu.

後藤大地 (daichi@freebsd.org) 作成年月日 Mon Feb 13 12:08:39 2006 更新年月日 Tue Oct 23 13:32:15 2007 FreeBSD 6.2-RELEASEまでに搭載されているunionfsにはいくつかの問題があった。問題は、大きく分けて2つの領域に分類することができる。unionfsにおける仕様が曖昧な部分に起因する問題と、FreeBSD unionfsのロックの実装に関する問題である。 FreeBSD unionfsの2つの問題： unionfsにおける仕様が曖昧な部分に起因する問題 FreeBSD unionfsのロックの実装に関する問題 この結果、CD9660ファイルシステムに対してunionfsをかぶせて使用するような場合にいくつかの問題が起こっていた。このためFreeSBIEのようなシステムではunionfsをそのまま採

Here is a VMware Virtual Machine that can be used on VMware Player 1.0.1 and VMware Workstation 5.5.1. FreeBSD/i386 6.0-RELEASE default plain installation This zipball (about 66MB, extracted 200MB) contains smallest-as-possible installation image of FreeBSD/i386 6.0-RELEASE. Virtual machine configuration is as follows: 256MB memory One IDE virtual 20GB HDD (partitioned by sysinstall default) One I

FreeBSD is extremely robust. There are numerous testimonials of active servers with uptimes measured in years. The new Soft Updates1 file system optimizes disk I/O for high performance, yet still ensures reliability for transaction based applications, such as databases. Linux is well known for its reliability. Servers often stay up for years. However, disk I/O is non-synchronous by default, which

Problem RAID-1 (mirroring) is a popular approach to protect the system from a harddisk failure. It is either done in hardware or software. The usual hardware solution is to buy a RAID disk controller like the popular 3ware ATA RAID controllers and then not having to deal with any software incompatibilities because the system just sees one large physical disk. The software solution is less expensiv