I have some multi-threaded C code (compiled with GCC 4.4.3) which accesses shared variables. Although I've marked those variables with volatile to guard against compiler re-ordering, I'm concerned that processor out-of-order execution may cause my code to fail, and I'm looking for a "low-cost" method of guaranteeing ordering is maintained in my code.
For example, I have something like...
Where I need to ensure that the "task state" is only set to "task_ready" after the previous instructions have been committed. As the "task" is shared between threads, another thread seeing the state as "ready" may try to access its member variables, so it's vital that the tasks "prefix" and "instance" have been updated.
I know this is a common problem and mutexes and semaphores provide in-built memory barriers to address this problem but I'm trying to build a scalable application and I want to avoid their use if possible. I also know GCC provides built-in atomic operations but I see they involve locking the data-bus, and I've heard about system primitives like "smp_wmb()" but I'm not sure how to incorporate these into my "user-space" program as they are platform dependent.
Therefore can anyone provide pointers or advise on how best (in terms of scalability and speed) to guarantee ordering is maintained?
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)
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)
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)
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)
import-bug-from-debian(1) General Commands Manual import-bug-from-debian(1)NAME
import-bug-from-debian - Import bugs from Debian's BTS, and file them against Ubuntu in LP.
SYNOPSIS
import-bug-from-debian [options] bug...
import-bug-from-debian -h
DESCRIPTION
import-bug-from-debian clones bugs from Debian's BTS into Launchpad. Each bug listed on the command line has its initial report re-filed
against the same source package in Ubuntu. The Ubuntu bug is linked back to its Debian counterpart.
Each bug may be provided either as a bug number or URL.
OPTIONS -b, --browserless
Don't open the bug in a browser at the end.
-h, --help
Display a help message and exit.
-l INSTANCE, --lpinstance=INSTANCE
Use the specified instance of Launchpad (e.g. "staging"), instead of the default of "production".
-p PACKAGE, --package=PACKAGE
Launchpad package to file bug against, if not the same source package name as Debian. Useful for importing removal bugs filed
against ftp.debian.org.
--no-conf
Do not read any configuration files, or configuration from environment variables.
ENVIRONMENT
All of the CONFIGURATION VARIABLES below are also supported as environment variables. Variables in the environment take precedence to
those in configuration files.
CONFIGURATION VARIABLES
The following variables can be set in the environment or in ubuntu-dev-tools(5) configuration files. In each case, the script-specific
variable takes precedence over the package-wide variable.
IMPORT_BUG_FROM_DEBIAN_LPINSTANCE, UBUNTUTOOLS_LPINSTANCE
The default value for --lpinstance.
SEE ALSO ubuntu-dev-tools(5)AUTHORS
import-bug-from-debian was written by James Westby <james.westby@ubuntu.com>, and this manual page was written by Stefano Rivera <ste-
fanor@ubuntu.com>.
Both are released under the terms of the GNU General Public License, version 2.
ubuntu-dev-tools September 21 2010 import-bug-from-debian(1)