Sponsored Content
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
libmlib_mt(3LIB)						Interface Libraries						  libmlib_mt(3LIB)

NAME
libmlib_mt - multi-threaded mediaLib SYNOPSIS
cc [ flag... ] file... -lmlib_mt -lmlib [ library... ] #include <mlib.h> DESCRIPTION
Interfaces in this library provide functions for multimedia processing. Multi-threaded (MT) mediaLib is a software layer developed on top of mediaLib using OpenMP. When it is used with a large data set on a multi-processor system, MT mediaLib will partition data into subsets and process the subsets in parallel, thus greatly improving performance of applications that use mediaLib. INTERFACES
The shared object libmlib_mt.so.2 provides the same public interfaces as those defined in libmlib(3LIB). See Intro(3) for additional infor- mation on shared object interfaces. USAGE
There are two ways to use MT mediaLib. 1. Pre-load a multi-threaded mediaLib library during runtime by setting the LD_PRELOAD environment variable as follows before starting your application, in Bourne/Korn shell: LD_PRELOAD=libmlib_mt.so export LD_PRELOAD or in C shell: setenv LD_PRELOAD libmlib_mt.so In this way, you can take advantage of MT mediaLib without rebuilding your application. 2. Link your application with a multi-threaded mediaLib library directly as shown under SYNOPSIS. In this way, an MT mediaLib library is always used whenever your application is started. The parallelization of MT mediaLib is controlled, in part, by the PARALLEL environment variable. You can change its setting to adjust the degree of parallelization before starting your application, in Bourne/Korn shell: PARALLEL=n export PARALLEL or in C shell: setenv PARALLEL n where n is a positive integer for number of threads. Note that other factors also affect the degree of parallelization in MT mediaLib. FILES
/usr/lib/libmlib_mt.so.2 shared object /usr/lib/64/libmlib_mt.so.2 64-bit shared object ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWmlibt | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
Intro(3), libmlib(3LIB), attributes(5) mediaLib User's Manual SunOS 5.11 15 Oct 2007 libmlib_mt(3LIB)
All times are GMT -4. The time now is 10:50 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy