Programming :: RedHat 8.0 - Monitoring Context Switches
Apr 22, 2011
As a part of a school project I am working on monitoring context switches. I'm working on redhat 8.0, kernel version 2.4.18-14 and for some reason I keep getting unclassified reasons which causing context switches from a process to itself. I am trying to determine each context switch, what was the reason that causes it, whether time slice ended, or yielded, or went for waiting or returned from waiting or parameters changed or task ended to task forked or any possible reason.
But all the time I find that the only switches that I cannot determine the reason happens from a process to itself, all this unrecognized switches from process to itself happens only on interactive processes, and sometimes the need_resched flag is on and sometimes is off. What could possibly cause a context switch from a process to itself? Can a returning of a process with a lower (higher by number) priority from waiting cause a context switch?
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Jun 10, 2010
I have done some searching around the internet and this site, but I haven't found a good way to count the context switches on a thread in a c++ program I am running. I need to know if it get swapped off of a CPU for correct timing.
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Dec 18, 2009
I have a user complaining about performance:-
Quote: At times on our server, during more-or-less idle moments, context switching is around the 2000-3000 mark.When we run the app, we can get this up to the 500,000 CSs per second. Not only this, but at the same time, the CPUs go to >60% system (the kernel is having to do all that context switching after all), leaving only around 30% for user space. We think it is a possibility that the massive context switching is contributing significantly to our performance issues.
The server is a HP DL580 G5 with 4 x Intel Xeon E7340 @ 2.4Ghz.My issue is that I don't know if the contect switching is a problem or not.From what i've read those values are not necesserilly cause for concern.
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Apr 21, 2010
Found that RedHat Linux supports Context-Dependent Path Names in symbolic links using special reserved CDPN variables. Will it be possible to create a user-defined CDPN variable and use it in creating a symbolic link
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Dec 22, 2010
I have added apache application into redhat cluster. If the apache process failed, it will cause the service group fail over. I want to disable the application monitoring. I search throung Internet and it depends on the apache init script. If I change /etc/init.d/httpd status always return 0(success). THe service group will not fail over even apache failed.
However, I want to remain the application monitoring but stop failover. If the application like apache failed, I want Redhat cluster to try restart the application like 3 or 4 times. If restart failed, it will not failover.
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Mar 15, 2011
I have a coredump file which gives stacktrace. But I dont know which thread executed or any task switches happened before a crash happened from a given thread. is there anyway to find out.
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Aug 28, 2009
I had been working on a CPP code for sometime now, without being aware that some parts of its code, especially security related were not being compiled. Problem was like my product did not work for SSL mode. On analysis, I found that some part of CPP codes inside a switch(ENABLE_SSL_LIBRARY)were not getting compiled at all. And also that this gets set when we do newgrp crypto command on the box. This left me without lots of doubts. I wanted to understand how these switches work and if this switch was propreitary to my code or something related to Linux.
My questions now are:
1. Switches like the one mentioned above, are they user defined, for my particular code or are they related to Linux/GCC or makefiles?
2.If a user can define such switches to control code compilation, then need to know the concepts/procedures behind it. How is it done ?
Kindly excuse if these are very very basic. But since I could not get proper stuffs on google, I thought I should ask some experts here who could either explain me or point me to appropriate resources (links of articles / tutorials)
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Nov 23, 2010
I want to allow my program to be able to run in DEBUG mode. i.e., I want to be able to run ./program, and I want to be able to run ./program -v to show all the debug output. How do I go about setting up something like that?
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Mar 18, 2011
I am using multi threading programming. In this from one of the thread I am calling other module's function with function pointer as argument. When that module calls the callback function in which context the function runs(thread/process). As per my observation it looks like running in process context (main process).
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Feb 27, 2010
I've been playing around a bit with Xlib programming, and I'm just wondering if anyone knows of a good tutorial involving XContext's? Even if someone could explain the concept to me a bit.
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Mar 21, 2010
How to make a context menu for items in a QTreeView?
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Aug 17, 2010
I am trying to write a program that monitors when an lp or basically any sort of print command is issued. If a print command is detected I want to pause that job and ask the user if he / she wants to continue.
This program would run in the background all the time so it can't sit and eat up a lot of cpu. I tried a simple while loop that continuously monitored "ps" and that obviously boosted my cpu to 100%.
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Feb 4, 2011
NextPendingConnection () returns a new socket with respect to a new client. This new QSocket is passed to the connect () function which connects it to a SLOT 'xyz' with SIGNAL 'readyRead()'. Now in the SLOT 'xyz' how I am supposed to automate the monitoring of ALL connected sockets to see whether some data is available on them? One pathetic way would be to run all the sockets through a for loop and check each one of them for the data. Secondly, I read up on QSocketNotifier() here: [URL]. But I am not sure if that is the correct thing.
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Apr 5, 2011
Is there any way to make program in linux machine to make report when some files have been copy to another directory or machine and knows the users who copy the files, I am planning to make this program in c, honestly first time I want to make in python when I know about pyinotify and how easy to monitoring the file in machine, but the problem is I cannot integrate that script python to know the users who do that except for the one who create the file.
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Feb 12, 2010
I'm having some problems on the line with ***. This is from a OpenEntidade.java class file and I'm trying to update EmprestadorView's variables.
EmprestadorView.java
public class EmprestadorView extends FrameView {
...
OpenEntidade.java
-----------------
public class OpenEntidade extends javax.swing.JFrame {
[code]....
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Jan 22, 2011
I am customizing the CentOS and I want to change the complete look and feel of the OS. I know all the installation wallpapers and images comes from the rpm mentioned above.
Even I extracted the said rpm using rpm2cpip and have replaced the my customized images but not sure how can I prepare my new RPM to include that in a my build.
Does any have any clue or I should go for src.rpm?
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Mar 24, 2010
I've read there is a way to communicate without tradtional TCP/IP programming on Redhat Linux and Nehalem CPU with ethernet. I've tried to collect some related information with sample program codes, but failed to collect useful information.
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Sep 17, 2010
On Debian, if I want to compile some package X myself, but I don't want to spend time hunting down and installing its dependencies, I can issue the following command:
Code:
apt-get build-dep X
And apt (so long as it knows about package X) will install all the dependencies for me.Does the yum package manager on RedHat-based systems have a similar feature?
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Jan 11, 2011
I had Windows XP working. I then put in a new hard disk and installed Redhat 5 on it. rom then i could only boot into Redhat. Further, everyting is very slow. Anothe rproblem is that Redhat does not see my netwrok so I cannot get onto the Internet. I need to have the choice of booting into XP or Redhat.
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May 5, 2011
I cant mount a directory on red hat 5 from red hat 4 using fstab.I keep getting permission denied.I mount directories on the same red hat 5 sys from other red hat 5 and 2 old HPUX systems using fstab.When I try to telnet to it i get "no route to host."
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Aug 19, 2010
I'm running ubuntu 10.04 on a new pc I just bought. Every so often the monitor will just shut down and display a message: "no signal input". I'm sure the computer is still running though because the fan is still running and all lights etc. are still on. I've tried switching the monitor on and off and there is still no input signal, the only solution is to reboot the entire computer.
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Mar 21, 2011
I use vncviewer (win32) to connect to my SuSE 11.3 box. The SuSE box has the "standard" xinetd started Xvnc server running (includes the -inetd switch).
My client (the vncviewer) has to go through a firewall with limited ports available and so I use the command line:
Code:
However, if there is a problem with the connection, such that the client disconnects, it seems that subsequent request to the Xvnc server create a new session/display. The text in the client window reports "nobody's x11 desktop (host:1)", then "...(host:2)", then "...(host:3)" etc.
I have tried combining the display and the port parameters, like this:
Code:
Can anyone suggest an alternative way of reconnecting to a broken vnc session?
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Jan 9, 2010
I purchased a foot pedal [URL], which I want to use as a substitute for the ALT, CTRL and SHIFT key (Mainly in my texteditor, Emacs, where these modifiers are used a lot for commands). So instead of pressing ALT+x I want to press the left pedal + x. However, instead of going into the command mode it just types x to the screen. If I keep the pedal pressed, and type another x, it switches into command mode, like it should have done right away. The device seems to use HID, and lsusb gives:
Bus 005 Device 004: ID 1130:660c Tenx Technology, Inc.
Is there a way, how I can change the behaviour of the device?
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Apr 26, 2010
Sometimes when firefox is open, clicking the firefox icon on the taskbar to maximize firefox rotates my desktop to the next one over. Super annoying, as I have to go and rotate back. Is there a fix to this problem? I think it has something to do with a pop-up that never gets attention when it needs it. Unfortunately, I don't know a good way to reproduce this problem on command yet.
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Jun 21, 2010
Basically I have some Linux experience and have got myself an "old-but-good-machine".
I'm sure the Xubuntu 10.04 cd is OK as I can boot into it with my Windows laptop.
But... for whatever reason I can't boot it under the Live CD or Install options in my old computer?
As soon as I hit one of the options the monitor switches off after a few seconds?
I've tested the computer with a live backtrack cd and gparted live cd which both run fine so it must be something I'm missing in Xubuntu.
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Sep 12, 2010
I have just installed 10.04 x86 for my mom and while she is using it (tyrannically just browsing facebook/email/flash games) the screen randomly goes blank then back to normal again. This symptom generally worsens after a few minutes until it is unusable. Specs are as follows:
Athlon X2 5200+
3GB RAM
ATi 2400pro 256MB (using the standard out of the box drivers)
Also running compiz and emerald so that I was able to make the desktop look like OS X.
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May 10, 2011
I'm running Ubuntu 11.04 on my laptop. At work, we are beginning to tinker with running Ubuntu on our student systems (school district). The thing is, Unity and Gnome Shell are new enough that they are not considered right now as viable options to test in. That said, an alternative was needed that was quick on older systems yet very configurable. XFCE. So I installed XFCE on my Ubuntu machine. This way I can tinker with the interface as if I was a student but then I can bounce back to Unity which I do prefer for personal use. The thing is, the login screen switches over to XFCE's. Is there a way to get my regular Ubuntu login screen back?
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Jun 20, 2011
I have a question about bonded NICs and the switches they are connected to.
I have a server which needs to send a lot of data to another server quickly. Both have multiple GbE NICs. I understand what is required at the server end (I think) in that a pseudo-interface is created such as bond0 with the IP applied to that interface rather than eth0 and eth1.
My question relates to the connection between the servers, i.e. the switch. Is a specific type of switch required for this to work, as an IP will have 2 (or more) MAC addresses associated with it, or how does the switch decide to which port to route the traffic for the bond0 IP?
Also, will this only work when multiple connections are being made? What I mean is, will each individual TCP connection only use either the physical eth0 OR the physical eth1 interface, or can a single connection make use of the aggregated bandwidth, sending one packet to one physical interface and another to the other physical interface, using the bond0 IP as the destination?
What I am trying to work out is if I had a storage server connected to an application server and exporting storage using NFS or GlusterFS, would an aggregated link improve throughput?
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Aug 29, 2009
This morning I installed Slackware 13 i386 and started configuring it. I've got a problem as my laptop has turned off unexpectedly twice since I started using Slack 13. I don't know if it's related to Slackware 13 but it has never happened before on this laptop with Slackware 12.2 or any other system. The first guess would be overheating. I checked the laptop's BIOS but could not find anything related to cooling down.
The laptop seems quite hot but it's nothing unusual for it. I also noticed that acpi is not installed by default. Would it make much difference? The laptop is pretty new (6 months) and the cooling module seems to be clean. The only thing that differs from my previous installations is that for the first time I installed ATI's fglrx and enabled desktop effects. Could it be a buggy video driver?
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Jan 26, 2010
I'm configuring Nagios at the moment, but I'm doubting my approach to transparent switches a bit. It seems from reading the documentation that Nagios wants me to ignore transparent switches, although I also doubt this interpretation of mine.
A little example, a VPN:
Code:
demarcation point
|
[router]
/
[switch][switch]
| / |
[7 clients] [switch] [switch]
/ |
[6 clients] [4 clients] [5 clients]
As you can see, there are 22 clients connected to the router. Since switches don't have an address, they cannot be measured. But if I ignore the switches, the schema is an oversimplified picture of reality. So what I'm looking for is a way to display the switches, even though they don't have an address. What I did was, I created the switches as where they proper fully featured ones, and listening to 127.0.0.1 as address. Luckily, this tricked Nagios. And it works, but it's not very elegant. Is there a better way to approach this pseudo-problem? Perhaps a build-in I overlooked?
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