Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Memory Barriers for (Ubuntu) Linux (i686)
Special Forums UNIX and Linux Applications High Performance Computing Memory Barriers for (Ubuntu) Linux (i686) Post 302430730 by Corona688 on Friday 18th of June 2010 01:34:12 PM
Old 06-18-2010
The old system(usually known as linuxthreads) has been abandoned for many moons now. It was designed to operate without modifying the kernel, which made it a very strange beast -- it created pretend-thread processes with 100% shared memory, did all communication with signal traps, and had some very....unique bugs that turned out to be fundamental design flaws(zombie threads! Wow!)

So, no. It was not a high-performance threading model. There's only a very few things(like ulibc in embedded systems) that still stick with it these days.

With kernel 2.5 and later, they built enough things into the kernel to let them do threading properly. I've shown you bits of its code -- some fundamental things are almost down to the instruction level. NPTL is much, much better, and I've found it quite good.

Quote:
I wanted to avoid the pthreads syncrhonisation structures like mutexes because I sought to avoid their overhead and keep it scalable.
Yes, and the overhead you were worried about was the same atomic operations you're hellbent on using now. I've looked in its code and shown you some of it; it's not bloated.
Quote:
There are ways to distribute work such that mutexes aren't necessary as long as an ordering of instructions can be guaranteed, hence following your advice, I'll try those atomic instructions from GCC.
I remain stolidly unconvinced that spinlocking is more efficient than blocking. If your writer really can keep up with your readers, a proper queue might not block at all even in pthreads.
Quote:
But anyway, I needed something with more control than was on offer with something featuring a standard posix api.
Are you sure of that? You only discovered thread-specific data last week.
Last edited by Corona688; 06-18-2010 at 02:42 PM..
 

4 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Memory-waste in Ubuntu/Debian?

I have 512 mem on this laptop, though 'top' tells me I only have 380. However, Ubuntu is using 288 mb of memory, when I only have 3 terminals, running lynx, vim(for this file) and (of course) top. Considering it I have lynx running a 600 page txt file, which of course would eat some memory but 300?... (0 Replies)
Discussion started by: riwa
0 Replies

2. Linux

i686, x86 64, ppc

Hi, i am quite new to linux. I am interested in fedora linux distro. Fedora Project I dont know which one to choose, either i686, x86 64 or ppc. I prefer a live cd, coz its easy to use. And what is the difference between "Fedora Desktop Live Media" and "Fedora KDE Live Media". (3 Replies)
Discussion started by: superblacksmith
3 Replies

3. Programming

Getting the total virtual memory for ubuntu in c++

Hi guys , i need to get the total virtual memory in ubuntu but i need to write a C++ code for that, any idea on how to go about doing it? any references? or website that i can refer to ? (6 Replies)
Discussion started by: xiaojesus
6 Replies

4. Ubuntu

XP and Linux (Ubuntu) on same disk, Can I install Ubuntu on not-yet partitioned portion of disk?

My PC (Esprimo, 3 yeas old) has one hard drive having 2 partitions C: (80 GB NTFS, XP) and D: (120 GB NTFS, empty) and and a 200 MB area that yet is not-partitioned. I would like to try Ubuntu and to install Ubuntu on the not-partitioned area . The idea is to have the possibility to run... (7 Replies)
Discussion started by: C.Weidemann
7 Replies

LEARN ABOUT DEBIAN

ubuntu-dev-tools

ubuntu-dev-tools(5)						File Formats Manual					       ubuntu-dev-tools(5)

NAME

       ubuntu-dev-tools - Configuration for the ubuntu-dev-tools package.

DESCRIPTION

       The  ubuntu-dev-tools  package  is  similar in scope to the devscripts(1) package, providing a collection of scripts which may be of use to
       Ubuntu and Debian developers or others wishing to build Debian packages.

       Some of these scripts have options which may be configured  on  a  system-wide  and  per-user  basis.   These  options  are  configured	in
       devscripts.conf(5).

       All variables are described in the script's manpages. Package-wide variables begin with "UBUNTUTOOLS" and are listed below.

       Every script which reads the configuration files can be forced to ignore them by using the --no-conf command-line option.

ENVIRONMENT

       All ubuntu-dev-tools configuration variables can be set (and overridden) by setting them in the environment (unlike devscripts).

       In addition, several scripts use the following environment variables:

       UBUMAIL
	      Overrides  DEBEMAIL  and	DEBFULLNAME  when  the	target	is  clearly  Ubuntu.   Can  either  contain an e-mail address or Full Name
	      <email@example.org>.

       DEBEMAIL, DEBFULLNAME
	      As in devscripts(1).

PACKAGE-WIDE VARIABLES
       The currently recognised package-wide variables are:

       UBUNTUTOOLS_BUILDER
	      This specifies the preferred test-builder, one of pbuilder (default), sbuild, pbuilder-dist.

       UBUNTUTOOLS_DEBIAN_MIRROR
	      The preferred Debian archive mirror.  Should be of the form http://ftp.debian.org/debian (no trailing slash).  If not specified, the
	      master will be used.

       UBUNTUTOOLS_DEBSEC_MIRROR
	      The  preferred Debian security archive mirror.  Should be of the form http://security.debian.org (no trailing slash).  If not speci-
	      fied, the master will be used.

       UBUNTUTOOLS_UBUNTU_MIRROR
	      The preferred Ubuntu archive mirror.  Should be of the form http://archive.ubuntu.com/ubuntu (no trailing slash).  If not specified,
	      the master will be used.

       UBUNTUTOOLS_UBUNTU_PORTS_MIRROR
	      The preferred Ubuntu archive mirror.  Should be of the form http://ports.ubuntu.com (no trailing slash).	If not specified, the mas-
	      ter will be used.

       UBUNTUTOOLS_LPINSTANCE
	      The launchpad instance to communicate with. e.g. production (default) or staging.

       UBUNTUTOOLS_MIRROR_FALLBACK
	      Whether or not to fall-back to the master archive mirror.  This is usually the desired behaviour, as mirrors can	lag  the  masters.
	      If on a private network with only a local mirror, you may want to set this to no.  One of yes (default) or no.

       UBUNTUTOOLS_UPDATE_BUILDER
	      Whether or not to update the test-builder before each test build.  One of yes or no (default).

       UBUNTUTOOLS_WORKDIR
	      The directory to use for preparing source packages etc.  When unset, defaults to a directory in /tmp/ named after the script.

SEE ALSO

       devscripts(1), devscripts.conf(5)

AUTHORS

       This manpage was written by Stefano Rivera <stefanor@ubuntu.com>.

ubuntu-dev-tools						 December 19 2010					       ubuntu-dev-tools(5)
All times are GMT -4. The time now is 12:44 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy