Search Results

Search found 26742 results on 1070 pages for 'linux kernel'.

Page 322/1070 | < Previous Page | 318 319 320 321 322 323 324 325 326 327 328 329  | Next Page >

• High CPU usage - symptoms moving from server to server after bouncing

  - by grt3kl

  First off, I apologize if I didn't include enough information to properly troubleshoot this issue. This sort of thing isn't my specialty, so it is a learning process. If there's something I need to provide, please let me know and I'll be happy to do what I can. The images associated with my question are at the bottom of this post. We are dealing with a clustered environment of four WebLogic 9.2 Java application servers. The cluster utilizes a round-robin load algorithm. Other details include: Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_12-b04) BEA JRockit(R) (build R27.4.0-90_CR352234-91983-1.5.0_12-20071115-1605-linux-x86_64, compiled mode) Basically, I started looking at the servers' performance because our customers are seeing lots of lag at various times of the day. Our servers should easily handle the loads they are given, so it's not clear what's going on. Using HP Performance Manager, I generated some graphs that indicate that the CPU usage is completely out of whack. It seems that, at any given point, one or more of the servers has a CPU utilization of over 50%. I know this isn't particularly high, but I would say it is a red flag based on the CPU utilization of the other servers in the WebLogic cluster. Interesting things to note: The high CPU utilization was occurring only on server02 for several weeks. The server crashed (extremely rare; we are not sure if it's related to this) and upon starting it back up, the CPU utilization was normal on all 4 servers. We restarted all 4 managed servers and the application server (on server01) yesterday, on 2/28. As you can see, server03 and server04 picked up the behavior that was seen on server02 before. The CPU utilization is a Java process owned by the application user (appown). The number of transactions is consistent across all servers. It doesn't seem like any one server is actually handling more than another. If anyone has any ideas or can at least point me in the right direction, that would be great. Again, please let me know if there is any additional information I should post. Thanks!

  Read the article

• Two DHCP Servers, Block Clients for one of them?

  - by Rilindo

  I am building out a kickstart network that resides on a different VLAN uses its own DHCP server. For some reason, my kickstart clients kept getting assign IPs from my primary DHCP server. The way I have it set up is that I have a primary DHCP server on this router here: 192.168.15.1 Connected to that DHCP server is a switch with the IP of 192.168.15.2. My kickstart (Scientific Linux) server is connected to that switch on two ports: Port 2 - where the kickstart server communicates to the rest of the production network via eth0. The IP assigned to the server on that interface is 192.168.15.100 (on eth0). The details are: Interface: eth0 IP: 192.168.15.100 Netmask: 255.255.255.0 Gateway: 192.168.15.1 Port 7 - has it's own VLAN ID (along with port 8). The kickstart server is connected to that port with the IP of 172.16.15.100 (on eth1). Again, the details are: Interface: eth1 IP: 172.16.15.100 Netmask: 255.255.255.0 Gateway: none The kickstart server runs its own DHCP server and assigns them over the eth1. Most of the kick starts are built over the kickstart VLAN through port 8. To prevent the kickstart DHCP server from assigning addresses over the production network, I have the route setup like so: route add -host 255.255.255.255 dev eth1 At this point, the clients kept getting assign IPs from the 192.168.15.1 DHCP server. I need to figure out a way to block client requests from reaching that DHCP. Its should be noted that but I also build KVM hosts on the kickstart server as well, so I need those KVMs to have the ability to get DHCP requests from the 192.168.15.1 DHCP server via the bridge network once I finish resolved this particular problem. (Currently, they communicate via NAT). So what would be done to resolve this? Through iptables or some sort of routing I need to put in? I tried to limited to requests via IPtables on that interface, allowing DHCP requests for 172.16.15.x network: -A INPUT -i eth1 -s 172.16.15.0/24 -p udp -m udp --dport 69 -j ACCEPT -A INPUT -i eth1 -s 172.16.15.0/24 -p tcp -m tcp --dport 69 -j ACCEPT -A INPUT -i eth1 -s 172.16.15.0/24 -p udp -m udp --dport 68 -j ACCEPT -A INPUT -i eth1 -s 172.16.15.0/24 -p tcp -m tcp --dport 68 -j ACCEPT -A INPUT -i eth1 -s 172.16.15.0/24 -p udp -m udp --dport 67 -j ACCEPT -A INPUT -i eth1 -s 172.16.15.0/24 -p tcp -m tcp --dport 67 -j ACCEPT And rejects assignments on eth1 from 192.168.15.x network: -A FORWARD -o eth1 -s 192.168.15.0/24 -p udp -m udp --dport 69 -j REJECT -A FORWARD -o eth1 -s 192.168.15.0/24 -p tcp -m tcp --dport 69 -j REJECT -A FORWARD -o eth1 -s 192.168.15.0/24 -p udp -m udp --dport 68 -j REJECT -A FORWARD -o eth1 -s 192.168.15.0/24 -p tcp -m tcp --dport 68 -j REJECT -A FORWARD -o eth1 -s 192.168.15.0/24 -p udp -m udp --dport 67 -j REJECT -A FORWARD -o eth1 -s 192.168.15.0/24 -p tcp -m tcp --dport 67 -j REJECT Nope. :(

  Read the article

• How to link specific ports to specific domains with Apache virtual hosts?

  - by theJoe

  We have a forward-facing linux box running Apache HTTP server that is acting as a reverse proxy for several back-end servers. The servers are accessed through specific domain names and ports and are set up as virtual hosts within Apache as such: Listen 8001 Listen 8002 <Virtualhost *:8001> ServerName service.one.mycompany.com ProxyPass / http://internal.one.mycompany.com:8001/ ProxyPassReverse / http://internal.one.mycompany.com:8001/ RewriteEngine On RewriteCond %{REQUEST_METHOD} ^(TRACE|TRACK) RewriteRule .* - [F] </Virtualhost> <Virtualhost *:8002> ServerName service.two.mycompany.com ProxyPass / http://internal.two.mycompany.com:8002/ ProxyPassReverse / http://internal.two.mycompany.com:8002/ RewriteEngine On RewriteCond %{REQUEST_METHOD} ^(TRACE|TRACK) RewriteRule .* - [F] </Virtualhost> The proxy server has only one IP address, and both domains are pointing to it. Accessing internal.one via service.one works fine, as does accessing internal.two via service.two. Now the problem is that Apache does not take the requesting domain into account when accessing the virtual hosts. What I mean is that both domains work for both ports: requests for service.one:8002 proxies to internal.two:8002, and requests for service.two:8001 proxies to internal.one:8001, where ideally both these requests should be denied. I can get around this by creating more virtual hosts that explicitly deny these requests: NameVirtualHost *:8001 NameVirtualHost *:8002 <Virtualhost *:8001> ServerName service.two.mycompany.com Redirect permanent / http://errorpage.mycompany.com/ </Virtualhost> <Virtualhost *:8002> ServerName service.one.mycompany.com Redirect permanent / http://errorpage.mycompany.com/ </Virtualhost> But this is not an ideal solution, since we plan to add more services to the proxy, and each new port would need to be explicitly denied on all the other domains, and each new domain would need to be explicitly denied on all ports it is not utilizing. As we add more services, the number of virtual hosts can get out of hand quickly. My question, then, is whether there is a better way? Can we explicitly tie specific ports to specific domains in a virtual host so that only that domain-port combination is processed, and all other combinations are not? Things I’ve tried: Adding NameVirtualHost *:8001, etc. without the additional virtual hosts. Setting ProxyRequests On and Off, as well as ProxyPreserveHost On and Off Adding the server name or IP address to the virtual host header, e.g. <VirtualHost service.one.mycompany.com:8001> Using the <proxy> directive inside the virtual host directive. Lots and lots of googling. The proxy server is running CentOS 6.2 64-bit, Apache HTTPD server 2.2.15. As mentioned, the proxy server has only one IP address, and all the domains we are using are pointing to it.

  Read the article

• Have a server, need to figure out a method of backup

  - by PolishHurricane

  My company has an older Dell 2650 server running ArchLinux x64: http://www.dell.com/downloads/global/products/pedge/en/2650_specs.pdf (2 x 2.4GHz Intel Xeon w/around 3287 RAM according to "free -m") We use it to host our internal company site and to post some information from our orders to and we'd like the ability to keep it up as much as possible. What we require: - It needs to always be functional from 8am to 4pm for our data entry person to use it and others to do other things required on it. - If it goes down, we need a quick way to get the machine running again. - If it goes down, we would like to have the data backed up. Some of the major problems include: - The servers old and it may have memory issues - We don't know when one of the hard drives could fail - Our power goes out here once in a while We have a battery backup, but that's pretty much it and it's not for long term. If the server does go down, we have another system in place to store order information that comes in while it's down and repost it when it's back, but we need it up during the day. So we're wondering, what should we get for options? These are the things we thought of, sort of: Setup RAID 1, but that would involve wiping everything right? If we do that, how would we transfer the data over without messing up the server? We could buy an extra server or 2 off eBay for $100, the same model, is that practical or should we get something else? Should we buy a PC or another better server and host off that because it is if anything easier to exchange parts? Should we keep extra parts handy incase it implodes? Should we buy/use backup software? We hear drobo's are cool, but suck. Perhaps there is a software solution to this problem that backs up to another machine or gets us up and running again quickly. Also, if we are to purchase hardware, what is decent? Does anybody know of one for ArchLinux/Linux? We both know a ton about computers but we're kind of unsure what step to take with this, especially with this type of server. Thanks

  Read the article

• Why would a process monitoring script use exit 1; on finding no problems?

  - by user568458

  General question: On a Linux (Centos) server, if a process monitoring script run by cron is set to close with exit 1; rather than exit 0; on finding that everything is okay and that no action is needed, is that a mistake? Or are there legitimate reasons for calling exit 1; instead of exit 0; on the "Everything's fine, no action needed" condition? exit 0; on finding no problems seems to me to be more appropriate. But maybe there's something I'm not aware of. For example, maybe there's something specific to Cron? Or maybe there's a convention in process monitoring scripts that 'failure' means 'this script failed to need to fix a problem' (rather than what I would expect which is that exit 1; would mean 'the process being monitored has failed'?) My specific case: I'm looking at a process monitoring script written by my web hosting company. By process monitoring script, I mean a script executed by Cron on a regular basis that checks if an important system process is running, and if it isn't running, takes actions such as mailing an administrator or restarting the process. Here's the (generalised) structure of their script, for a service running on port 8080 (in this case, Apache Tomcat): SERVICE=$(/usr/sbin/lsof -i tcp:8080 | wc -l); if [ $SERVICE != 0 ]; then exit 1; else #take action fi Seems simple enough even for someone with limited knowledge like me, except the exit 1; part seems odd. As I understand it, exit 0; closes a program and signifies to the parent that executed the program that everything is fine, exit n; where n0 and n<127 signifies that there has been some kind of error or problem. Here, their script seems to go against that rule - it calls exit 1; in the condition where everything is fine, and doesn't exit after taking remedial action in the problem condition. To me, this looks like a mistake - but my experience in this area is limited. Are there cases where calling exit 1; in the "Everything's fine, no action needed" condition is more appropriate than calling exit 0;? Or is it a mistake? Wider context is pretty simple. It's a Centos VPS, running Plesk. The script is being called by Cron via Plesk's "Scheduled tasks" Cron manager. There's no custom layer between Cron and this script that would respond in an unusual way to the exit call. It's a fairly average, almost out-of-the box Plesk-managed Centos VPS (in so far as there is such a thing). The process being monitored by this script is Apache Tomcat.

  Read the article

• Can't recover hard drive

  - by BreezyChick89

  My drive got corrupt after a thunderstorm. It used to be 1 partition of 2.5tb but now it shows 2 partitions. It's weird because 300gig free space is about how much it had before corrupting, but it was part of the first partition. I tried $ sudo resize2fs -f /dev/sdb1 Resizing the filesystem on /dev/sdb1 to 536870911 (4k) blocks. resize2fs: Can't read an block bitmap while trying to resize /dev/sdb1 Please run 'e2fsck -fy /dev/sdb1' to fix the filesystem after the aborted resize operation. sudo e2fsck -f /dev/sdb1 e2fsck 1.42 (29-Nov-2011) The filesystem size (according to the superblock) is 610471680 blocks The physical size of the device is 536870911 blocks Either the superblock or the partition table is likely to be corrupt! Abort? n .... Error reading block 537395215 (Invalid argument) while reading inode and block bitmaps. Ignore error<y>? yes Force rewrite<y>? yes Error writing block 537395215 (Invalid argument) while reading inode and block bitmaps. Ignore error<y>? yes ... A lot of these. I can't use e2fsck -y because the first question aborts if I say "y". If I put a weight on the 'y' key it fails because none of the errors were really fixed. I asked this question before and tried using gparted but gparted fails because the first thing it does is: e2fsck -f -y -v /dev/sdb1 giving the same error. The disk status says healthy. There are no bad blocks. This is very frustrating because I can see the data in testdisk and it looks like it's all there. I already bought another 2.5tb drive and made a clone using dd. The next step if I can't fix this is to wipe that drive and just move the data with testdisk, but it seems certain folders will copy infinitely until the drive is full because of symlinks or errors so it's also a difficult option. sudo fdisk -l Disk /dev/sdb: 2500.5 GB, 2500495958016 bytes 255 heads, 63 sectors/track, 304001 cylinders, total 4883781168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x0005da5e Device Boot Start End Blocks Id System /dev/sdb1 * 2048 4294969342 2147483647+ 83 Linux sudo badblocks -b 4096 -n -o badfile /dev/sdb 610471680 536870911 badfile is empty I also tried changing the superblock with "fsck -b" but all of them are the same.

  Read the article

• Simultaneous launch of Multiple Kernels using CUDA for a GPU

  - by cudadev

  Is it possible to launch two kernels that do independent tasks, simultaneously. For example if I have this Cuda code // host and device initialization ....... ....... // launch kernel1 myMethod1 <<<.... (params); // launch kernel2 myMethod2 <<<..... (params); Assuming that these kernels are independent, is there a facility to launch them at the same time allocating few grids/blocks for each. Does CUDA/OpenCL have this provision.

  Read the article

• Installing ruby1.8 failed

  - by Subhransu

  I was trying to install ruby on my remote server I got this error: The Command: sudo apt-get install ruby1.8 Error : W: Not using locking for read only lock file /var/lib/dpkg/lock E: Unable to write to /var/cache/apt/ E: The package lists or status file could not be parsed or opened. then I tried : sudo dpkg -- configure -a Output: dpkg: need an action option Type dpkg --help for help about installing and deinstalling packages [*]; Use `dselect' or `aptitude' for user-friendly package management; Type dpkg -Dhelp for a list of dpkg debug flag values; Type dpkg --force-help for a list of forcing options; Type dpkg-deb --help for help about manipulating *.deb files; Options marked [*] produce a lot of output - pipe it through `less' or `more' ! What should I do ?

  Read the article

• Linux accessibility: Slow Keys causing duplicate key strokes

  - by skypanther

  I'm exploring the accessibility features within Gnome and having trouble with Slow Keys. My input is always doubled. Press a key briefly and I get nothing as you'd expect. Press just a bit longer and which ever key I'm pressing is input twice. Hello becomes HHeelllloo. I'm running Debian Lenny 5.0.6, kernel 2.6.26-2-686, GNOME Desktop 2.22.3 running within a VirtualBox session. I did some googling and didn't find others having similar troubles. Maybe it's a vbox thing? Any ideas how to fix this so I don't get the duplicates? It makes it impossible to log back in when the screen lock kicks on!

  Read the article

• Can I make a "TCP packet modifier" using tun/tap and raw sockets?

  - by benhoyt

  I have a Linux application that talks TCP, and to help with analysis and statistics, I'd like to modify the data in some of the TCP packets that it sends out. I'd prefer to do this without hacking the Linux TCP stack. The idea I have so far is to make a bridge which acts as a "TCP packet modifier". My idea is to connect to the application via a tun/tap device on one side of the bridge, and to the network card via raw sockets on the other side of the bridge. My concern is that when you open a raw socket it still sends packets up to Linux's TCP stack, and so I couldn't modify them and send them on even if I wanted to. Is this correct? A pseudo-C-code sketch of the bridge looks like: tap_fd = open_tap_device("/dev/net/tun"); raw_fd = open_raw_socket(); for (;;) { select(fds = [tap_fd, raw_fd]); if (FD_ISSET(tap_fd, &fds)) { read_packet(tap_fd); modify_packet_if_needed(); write_packet(raw_fd); } if (FD_ISSET(raw_fd, &fds)) { read_packet(raw_fd); modify_packet_if_needed(); write_packet(tap_fd); } } Does this look possible, or are there other better ways of achieving the same thing? (TCP packet bridging and modification.)

  Read the article

• java TrayIcon using image with transparent background

  - by Jack

  I am using the following code to set a tray icon in Windows and Linux. It works wonderful in Windows and works okay in Linux. In Linux (Ubuntu) I have my panel set to be (somewhat) transparent and when I add a GIF (with a transparent background) the background of the icon shows up all grey and ugly (see image, green diamond "!")....Any ideas on how to make the GIF image I am adding "keep" its transparent background? and the image I am using, if you'd like to test: import java.awt.*; import java.awt.event.*; public class TrayFun { static class ShowMessageListener implements ActionListener { TrayIcon trayIcon; String title; String message; TrayIcon.MessageType messageType; ShowMessageListener( TrayIcon trayIcon, String title, String message, TrayIcon.MessageType messageType) { this.trayIcon = trayIcon; this.title = title; this.message = message; this.messageType = messageType; } public void actionPerformed(ActionEvent e) { trayIcon.displayMessage(title, message, messageType); } } public static void main(String args[]) { Runnable runner = new Runnable() { public void run() { if (SystemTray.isSupported()) { final SystemTray tray = SystemTray.getSystemTray(); Image image = Toolkit.getDefaultToolkit().getImage("green_info.png"); PopupMenu popup = new PopupMenu(); final TrayIcon trayIcon = new TrayIcon(image, "The Tip Text", popup); trayIcon.setImageAutoSize(true); MenuItem item = new MenuItem("Close"); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { tray.remove(trayIcon); } }); popup.add(item); try { tray.add(trayIcon); } catch (AWTException e) { System.err.println("Can't add to tray"); } } else { System.err.println("Tray unavailable"); } } }; EventQueue.invokeLater(runner); } }

  Read the article

• (simple) linux HA with vmware vsphere?

  - by derhelge

  I hope my upcoming question is specific enough, and you are able and willing to support :-) We have several openSUSE VMs in an ESX-Cluster (three ESX-Servers) with an attached iSCSI-SAN. All of those Linux VMs are "single point of failure"-configured, which means in the case of a Web-Server: LAMP, storage, etc. everything on this machine. This was very simple and in case of a failure (in the last years: kernel panics or apache crashes) a simple reboot triggered by a script did it. But the problem is: How to upgrade/maintain the w(eb-)application or the underlying OS without downtime? This wasn't really managable and i did this in the early morning ;) How can i achieve a "simple" High-Availability Cluster now? I thought of: DRBD with heartbeat with 2 VMs. And for the storage a RDM (raw device mapped) LUN and change the read-write-permissions for both VMs. Is this a good idea? Anyone has a better solution?

  Read the article

• How do I write x86 Debug registers from user space on OSX?

  - by nall

  I'd like to play around with the debug MSRs defined in the x86 spec (DR0-7) from my OSX user-space program. Unfortunately, these require CPL == 0 (aka ring 0). I've thumbed through the OSX syscalls and with the exception of kernel_debug nothing really jumps out as a way to access these. It may be the case that they are only available via some higher level interface like kernel_debug, but it's unclear to me if that's the case or if I just haven't found the magic invocation to get to them. Anyone know how to do this?

  Read the article

• FireLog: proper installation...

  - by kent

  I have installed the firewiresdk26 on my dev mac... and in the Tools/ directory is FireLog. I have run the FireLog 2.0.0.pkg installer on my dev mac, but the payload it deploys is installed in my /System/Library tree, as opposed to my /Developer/SDKs tree. so when I try to include the header iokit/firewire/FireLog.h it does not get found. am I missing something? or doing something wrong? or is this an error in the installer (either FW26 or FireLog installers?) I realize that the FireLog installer is intended to be run on the machine to be debugged remotely and thus it makes sense that the framework is placed in the /System/Library path, however none of the installers gets it into my developer path... I guess I just have to move it over there by hand, but before I do that I wanted to see if I'm just overlooking something silly and need to read the docs with more concentration or something... anyone run into this before? [thx]

  Read the article

• Daemon program that uses select() inside infinite loop uses significantly more CPU when ported from

  - by Jake

  I have a daemon app written in C and is currently running with no known issues on a Solaris 10 machine. I am in the process of porting it over to Linux. I have had to make minimal changes. During testing it passes all test cases. There are no issues with its functionality. However, when I view its CPU usage when 'idle' on my Solaris machine it is using around .03% CPU. On the Virtual Machine running Red Hat Enterprise Linux 4.8 that same process uses all available CPU (usually somewhere in the 90%+ range). My first thought was that something must be wrong with the event loop. The event loop is an infinite loop ( while(1) ) with a call to select(). The timeval is setup so that timeval.tv_sec = 0 and timeval.tv_usec = 1000. This seems reasonable enough for what the process is doing. As a test I bumped the timeval.tv_sec to 1. Even after doing that I saw the same issue. Is there something I am missing about how select works on Linux vs. Unix? Or does it work differently with and OS running on a Virtual Machine? Or maybe there is something else I am missing entirely? One more thing I am sure sure which version of vmware server is being used. It was just updated about a month ago though. Thanks.

  Read the article

• How to define GPS module in Android?

  - by Osama Gamal

  I'm porting android to Devkit8000 which is a BeagleBoard clone. I have a GPS module connected on /dev/ttyS0. I could successfully get NMEA output when writing "cat /dev/ttyS0" in the terminal emulator. I want to know how to let android know that there is a GPS module on /dev/ttyS0 and it is outputting NMEA standard? To be able to use the android.location class with it! Is there something to edit in the android's source? adding driver for example, writing a code with android-ndk or what?

  Read the article

• How to configure oracle instantclient for mono?

  - by funwithcoding

  Mono is really awesome. Some of our applications worked in linux out of the box even without recompiling the binary. However I am having tough time to configure oracle instantclient to use it with mono. I installed instantclient on a CentOS VM(by installing instantclient rpm) but however I did not find TNSNAMES.ORA anywhere. I searched for oracle and I found the following path contains the oracle libraries. [root@bagvapp rupert]# ll /usr/lib/oracle/11.2/client/lib/ total 143280 -rw-r--r-- 1 root root 7456 Aug 14 2009 cobsqlintf.o -rw-r--r-- 1 root root 342 Aug 14 2009 glogin.sql lrwxrwxrwx 1 root root 17 Mar 9 06:52 libclntsh.so -> libclntsh.so.11.1 -rw-r--r-- 1 root root 40088477 Aug 14 2009 libclntsh.so.11.1 -rw-r--r-- 1 root root 6986848 Aug 14 2009 libnnz11.so lrwxrwxrwx 1 root root 15 Mar 9 06:52 libocci.so -> libocci.so.11.1 -rw-r--r-- 1 root root 1879549 Aug 14 2009 libocci.so.11.1 -rw-r--r-- 1 root root 89377610 Aug 14 2009 libociei.so -rw-r--r-- 1 root root 152304 Aug 14 2009 libocijdbc11.so -rw-r--r-- 1 root root 1501651 Aug 14 2009 libsqlplusic.so -rw-r--r-- 1 root root 1218075 Aug 14 2009 libsqlplus.so -rw-r--r-- 1 root root 777979 Aug 14 2009 libsqora.so.11.1 -rw-r--r-- 1 root root 1996228 Aug 14 2009 ojdbc5.jar -rw-r--r-- 1 root root 2111220 Aug 14 2009 ojdbc6.jar -rw-r--r-- 1 root root 298388 Aug 14 2009 ottclasses.zip drwxr-xr-x 3 root root 4096 Mar 9 06:52 precomp -rw-r--r-- 1 root root 37807 Aug 14 2009 xstreams.jar no TNSPING available, no TNSNAMES.ORA, Now how to configure the mono to use this as the oracle client? and how to specify oracle database in app.config connection string section? Though mono is a powerful framework, seems like it is having problems like linux does, all the documentation is only available in mailing lists and whatever is available on official site is either outdated or not clear for normal user. Hope things will change soon and Mono will THE programming framework for linux.

  Read the article

• Memory assignment of local variables

  - by Mask

  void function(int a, int b, int c) { char buffer1[5]; char buffer2[10]; } We must remember that memory can only be addressed in multiples of the word size. A word in our case is 4 bytes, or 32 bits. So our 5 byte buffer is really going to take 8 bytes (2 words) of memory, and our 10 byte buffer is going to take 12 bytes (3 words) of memory. That is why SP is being subtracted by 20. Why it's not ceil((5+10)/4)*4=16?

  Read the article

• About fork system call and global variables

  - by lurks

  I have this program in C++ that forks two new processes: #include <pthread.h> #include <iostream> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <cstdlib> using namespace std; int shared; void func(){ extern int shared; for (int i=0; i<10;i++) shared++; cout<<"Process "<<getpid()<<", shared " <<shared<<", &shared " <<&shared<<endl; } int main(){ extern int shared; pid_t p1,p2; int status; shared=0; if ((p1=fork())==0) {func();exit(0);}; if ((p2=fork())==0) {func();exit(0);}; for(int i=0;i<10;i++) shared++; waitpid(p1,&status,0); waitpid(p2,&status,0);; cout<<"shared variable is: "<<shared<<endl; cout<<"Process "<<getpid()<<", shared " <<shared<<", &shared " <<&shared<<endl; } The two forked processes make an increment on the shared variables and the parent process does the same. As the variable belongs to the data segment of each process, the final value is 10 because the increment is independent. However, the memory address of the shared variables is the same, you can try compiling and watching the output of the program. How can that be explained ? I cannot understand that, I thought I knew how the fork() works, but this seems very odd.. I need an explanation on why the address is the same, although they are separate variables.

  Read the article

• Help, my CentOS servers keep going down , No route to host after a random uptime [closed]

  - by user249071

  Hello , I have a couple of Centos linux servers, that have a very simple task, they run nginx + fastcgi for php , and some NFS mounts between them, readonly They have some RPC commands to start some downloading processes with wget, nothing fancy , from a main server, but their behavior is very unstable, they simply go down, we tried to monitor ram , processor usage, even network connections, they don't load up so much, max network connections up to... 250 max, 15% processor usage and memory , well, doesn't even fill up, 2.5GB from 8GB max , I have no ideea why can a linux server go down like that, they aren't even public servers, no domain names installed no public serving, for sites. The only thing that I've discovered was that if i didn't restart the network service every couple of hours or so... the servers were becoming very slow, starting apps very slow, but not repoting a high usage of resources...Maybe Centos doesn't free the timeout connections, or something like that...It's based on Red Hat right? I'm not a linux expert , but I'm sure that there are a few guys out there that can easily have an answer to this , or even have some leads to what i can do ... I haven't installed snort, or other things to view if we have some DOS attacks, still the scheduled script that restarts the network each hour should put the system back online, and it doesn't.... Thank you in advance

  Read the article

• Link list usage in system programming

  - by Pwn

  Hi, in spite of having so many efficient data structures, why is only linked list used so heavily in systems programming? Is it because it allows least usage of heap/less buggy code? Regards, Pwn

  Read the article

• starting oracle 10g on ubuntu, Listener failed to start.

  - by tsegay

  I have installed oracle 10g on a ubuntu 10.x, This is my first time installation. After installing I tried to start it with the command below. tsegay@server-name:/u01/app/oracle/product/10.2.0/db_1/bin$ lsnrctl LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 29-DEC-2010 22:46:51 Copyright (c) 1991, 2005, Oracle. All rights reserved. Welcome to LSNRCTL, type "help" for information. LSNRCTL> start Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait... TNSLSNR for Linux: Version 10.2.0.1.0 - Production System parameter file is /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora Log messages written to /u01/app/oracle/product/10.2.0/db_1/network/log/listener.log Error listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1))) TNS-12555: TNS:permission denied TNS-12560: TNS:protocol adapter error TNS-00525: Insufficient privilege for operation Linux Error: 1: Operation not permitted Listener failed to start. See the error message(s) above... my listener.ora file looks like this: # listener.ora Network Configuration File: /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora # Generated by Oracle configuration tools. SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = PLSExtProc) (ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1) (PROGRAM = extproc) ) ) LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) (ADDRESS = (PROTOCOL = TCP)(HOST = acct-vmserver)(PORT = 1521)) ) ) I can guess the problem is with permission issue, But i dont know where I have to do the change on permission. Any help is appreciated ...

  Read the article

• A question for retrieve minix os version

  - by majnun

  Hi guys i'm having a project for the university in which (above others ) i have to get the minix os version from kernell call.I'm not a very experienced programmer so this is what i have come to (with some help ) int main (int argc, char *argv[] ) { char M3ca1[23]; message ml; m.m_u.m_m1.m3ca1= OS_VERSION; char temp=_syscall(MM,69,&m); printf("the os version is %c\n",temp); return 0; } and i get multiple errors.IF you have any ideas it would be greatly appreciated.

  Read the article

• "STI", in the protected mode,CPU will restart.

  - by user299668

  INTEL X86 Platform. My programme run start at 2M absolute address in protected mode,everything seems ok, but when i enable interrupt with "sti", the CPU will restart. Why? is there any necessary initialization before "enbale interrupt"? i have setup the idtptr, but it seems no work.

  Read the article

• Need a way to determine if a file is done being written to.

  - by Khorkrak

  The situation I'm in is this - there's a process that's writing to a file, sometimes the file is rather large say 400 - 500MB. I need to know when it's done writing. How can I determine this? If I look in the directory I'll see it there but it might not be done being written. Plus this needs to be done remotely - as in on the same internal LAN but not on the same computer and typically the process that wants to know when the file writing is done is running on a Linux box with a the process that's writing the file and the file itself on a windows box. No samba isn't an option. xmlrpc communication to a service on that windows box is an option as well as using snmp to check if that's viable. Ideally Works on either Linux or Windows - meaning the solution is OS independent. Works for any type of file. Good enough: Works just on windows but can be done through some library or whatever that can be accessed with Python. Works only for PDF files. Current best idea is to periodically open the file in question from some process on the windows box and look at the last bytes checking for the PDF end tag and accounting for the eol differences because the file may have been created on Linux or Windows.

  Read the article

< Previous Page | 318 319 320 321 322 323 324 325 326 327 328 329  | Next Page >