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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..
 

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page_util_quote(3tcl)					      Parser generator tools					     page_util_quote(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME
page_util_quote - page character quoting utilities SYNOPSIS
package require page::util::quote ?0.1? package require snit ::page::util::quote::unquote char ::page::util::quote::quote'tcl char ::page::util::quote::quote'tclstr char ::page::util::quote::quote'tclcom char _________________________________________________________________ DESCRIPTION
This package provides a few utility commands to convert characters into various forms. API
::page::util::quote::unquote char A character, as stored in an abstract syntax tree by a PEG processor (See the packages grammar::peg::interpreter, grammar::me, and their relations), i.e. in some quoted form, is converted into the equivalent Tcl character. The character is returned as the result of the command. ::page::util::quote::quote'tcl char This command takes a Tcl character (internal representation) and converts it into a string which is accepted by the Tcl parser, will regenerate the character in question and is 7bit ASCII. The string is returned as the result of this command. ::page::util::quote::quote'tclstr char This command takes a Tcl character (internal representation) and converts it into a string which is accepted by the Tcl parser and will generate a human readable representation of the character in question. The string is returned as the result of this command. The string does not use any unprintable characters. It may use backslash-quoting. High UTF characters are quoted to avoid problems with the still prevalent ascii terminals. It is assumed that the string will be used in a double-quoted environment. ::page::util::quote::quote'tclcom char This command takes a Tcl character (internal representation) and converts it into a string which is accepted by the Tcl parser when used within a Tcl comment. The string is returned as the result of this command. BUGS, IDEAS, FEEDBACK This document, will undoubtedly contain bugs and other problems. Please report such in the category page of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have. KEYWORDS
page, parser generator, quoting, text processing CATEGORY
Page Parser Generator COPYRIGHT
Copyright (c) 2007 Andreas Kupries <andreas_kupries@users.sourceforge.net> page 1.0 page_util_quote(3tcl)
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