The Linux kernel is the operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software.

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MAC to MAC MII interface not working [migrated]

I have a MAC to MAC MII interface between MPC8569 processor and BCM68610 controller , whose schematic design is followed from here. My linux kernel version is 2.6.32. I want to ping one device from ...
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8 views

What are the advantages NAPI before the IRQ Coalesce?

As known there are two approach to avoid some overheads of hardware interrupts in highload networks, when there are too many hardware interrupts, that switching to them takes too much time. It is very ...
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1answer
256 views

Scientific Linux: soft lockup on quad opteron system

After an impressive uptime of 550 days without trouble our quad opteron system turned into a corrupted system a few days after I mounted an nfs-share from a FreeNAS-box. Ongoing sessions remained ...
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1answer
19 views

IPSEC stack low speed

I am working on Openswan IPSEC Implementation for Linux-kernel 2.6.35.9 My concern is when i do speed test using IPSEC kernel Images and without running IPSEC service i get speed of 40Mbps and ...
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1answer
33 views

My server boots a kernel I don't recognize

On my dedicated server I'm running Debian 7.5 as an OS. I have installed OpenVZ for amd64 architecture to use the benefits of virtualization but after successfully installing it (following these ...
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1answer
23 views

Warning :mounting fs with errors, running e2fsck is recommended

Linux server will hang and when I restart it will take around 2 hours to come up and resume normal operations. I checked the system log files and found mounting fs with errors, running e2fsck is ...
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1answer
49 views

How to disable ipv6 support in Linux entirely?

We are currently setting up a some local network servers to run in a full ipv4 network. I can be sure, that this network don't have ipv6 support, and never will. Next to that, partially because of ...
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5answers
2k views

tc u32 — how to match L2 protocols in recent kernels?

I have a nice shaper, with hashed filtering, built at a linux bridge. In short, br0 connects external and internal physical interfaces, VLAN tagged packets are bridged "transparently" (I mean, no VLAN ...
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5 views

Does the guest OS need updates/changes after changing the number of cores in VMware Player? [migrated]

I installed ubuntu on a vm in VMware Player and forgot to change the number of cores from 1 to 8. If I change that now will the linux kernel need to be recompiled or anything like that or will it just ...
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1answer
34 views

Windows multicast NLB with Linux clients

I'm (on behalf of a client, anyway) having some troubles with Linux accessing a multicast NLB cluster hosted on Hyper-V (waiting for more information on what version, but I don't think the version is ...
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1answer
74 views

Unidentifiable processes under Redhat Linux

Upon issuing a ps ax command on a server I see the following processes that I can't identify. Googling them yields nothing useful. Does anybody know what these are or how I would track them down? The ...
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13 views

Why autoconf.h is not copied automatically to its place? [migrated]

I'm working on a clean Debian 7.7 install. After the install everything was working fine except the webcam in Iceweasel browser. After reading a lot I found that the best solution is to install ...
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1answer
84 views

enable fanotify on oracle redhat linux kernel 2.6.39-400

As a newbie in linux environment, I am trying to install clamav daemon, which is clamd, on oracle redhat linux 6 kernel EUK 2.6.39-400. It needs to have fanotify enabled in the kernel. As I see there ...
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2answers
2k views

Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console ...
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48 views

INFO : task events/2:69 blocked for more than 120 seconds

I'm using RHEL 6.3 running on VMWare vsphere and aproximatively every month there is this error message and application running above hang until I restart the server: "echo 0 > ...
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0answers
59 views

linux not replying to an arp request

I am running linux 3.14 on a system with 2 interfaces. on the first interface, i can access our local network. on the second interface, arp packets come in but linux doesn't send out reply. is it ...
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0answers
40 views

The default value for vm.dirty_background_ratio

Wondering why the default value for "vm.dirty_background_ratio" from Linux Server (CentOS and Ubuntu) is set to 40. Is this just a recommendation for safety? Or is there any particular reason why? ...
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48 views

Utility to list and modify kernel modules loaded during system startup

How do I list all kernel modules loaded while system startup? Is there a user space utility to list and modify the modules loaded during system startup? I am working on RHEL6 Desktop and RHEL6 ...
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1answer
41 views

View full program command line arguments in OOM killer logs

Is it possible to view full program command line arguments in OOM killler logs ? What I see now in /var/log/syslog is Memory cgroup out of memory: Kill process 29187 (beam.smp) score 998 or sacrifice ...
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1answer
937 views

web server “task blocked for more than 120 seconds”

my web server is down every 2 days. it became unresponsive and I can only see the message below on the console. task **** blocked for more than 120 seconds. The only way to bring it up is resetting ...
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1answer
56 views

Apply patch to custom kernel manually [closed]

I compiled a RHEL based kernel with a script. I've come to know that our version of kernel is vulnerable to attack and we need to apply security patches. ...
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2answers
10k views

How do I set the default kernel parameters in CentOS for all existing and future kernels?

I'd like to remove the rhgb and quiet kernel parameters which are used by default when the kernel is booted in CentOS 6, but I want this to apply to all currently installed kernels as well as any ...
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1answer
368 views

Cause of page fragmentation on “large” server with xfs, 20 disks and Ceph

Any insight from someone with a bit of experience in the linux IO system would be helpful. Here is my story: Recently brought up a cluster of six Dell PowerEdge rx720xds to serve files via Ceph. ...
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2answers
389 views

Linux (non-transparent) per-process hugepage accounting

I've recently converted some java apps to run with linux manually-configured hugepages, as desribed here. I point out "manually-configured" because they are not transparent hugepages, which gave us ...
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5answers
954 views

MySQL 5.5 degraded performance in linux kernel 3.2 compared to 2.6

Our database servers (mainly based on the Debian stable packages (=currently Wheezy) seem to have about 4 times more load for the same workload in kernel 3.2.0-4-amd64 then in it's previous ...
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1answer
53 views

how to determine who is using the slabs?

Is there any way to figure out who or what is allocating size-256 slabs, like in the slabtop output below? I had to reboot a server yesterday that had 5G out of 8G RAM in size-256 slabs and was ...
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28 views

systemrescuecd 4.3.1: parted cannot inform kernel of change

I am trying to use parted (3.2) on systemrescuecd (4.3.1), but keep getting the error message similar to below. Error: Partition(s) 2, 3, 4 on /dev/sdd have been written, but we have been unable to ...
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0answers
79 views

task fstrim blocked for more than 120 seconds

I'm experiencing random crashes on my system. I've narrowed the problem to the fstrim program that's launched weekly by cron. In the console, I've got a set of blocked tasks among whigetch I find ...
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1answer
133 views

WANem doesn't boot after install

I'm using WANem live cd (based on knoppix) to perform network bandwidth tests. In order to keep the current configuration, I've installed it on hard disk (using the gui installation tool provided ...
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2answers
10k views

Effects of configuring vm.overcommit_memory

My VPS web server running on CentOS 5.4 (Linux kernel 2.6.16.33-xenU) irregularly (like once a month give or take a few weeks) becomes unresponsive due to oom-killer kicking in. Monitoring of the ...
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1answer
424 views

Kernel panic - not syncing: VFS: Unable to mount root

I uploaded a centos 6.2 VMDK to s3 and then converted it to volume using ec2 import volume. Then i took the snapshot of the volume and deleted it.Now I am trying to create a instance from the snapshot ...
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1answer
928 views

RHEL 6.0 upgrading kernel from 2.6.32-71.el6.x86_64 to 2.6.32-358.2.1.el6.x86_64

[root@localhost ~]# rpm -ivh kernel-2.6.32-358.2.1.el6.x86_64.rpm error: Failed dependencies: bfa-firmware < 3.0.3.1 conflicts with kernel-2.6.32-358.2.1.el6.x86_64 [root@localhost ~]# rpm ...
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0answers
121 views

shorewall can'T start: UNTRACKED state requires Raw Table in your kernel and iptables

I'm trying setting up my firewall and installed and configured shorewall. Unfortunately I tried to directly configure iptables first, but this didn't work. When I start shorewall, I get this messages ...
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1answer
395 views

dummy network interface in Linux

When i create a dummy network interface and then bring it up it show up being in UNKNOWN state: root@5b8dd2855a9c:# ip l a boom type dummy root@5b8dd2855a9c:# ip l show boom 58: boom: ...
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0answers
52 views

“Nosy Neighbor” and the CFQ scheduler

I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all ...
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2answers
233 views

order 4 allocation failure disaster

Some environment details first: Hardware: Intel Server Board S2600GZ 2 x Intel Xeon CPU E5-2620 64GB DDR3 RAM Intel RAID Controller RS2BL (LSI SAS2108) with 4TB LVM Volume made of SAS disks ...
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1answer
3k views

CentOS 6.3 task blocked for more than 120 seconds

Recently have been getting Zabbix alerts about our mail system being unavailable, the uptime on the machine is 30+ days. I've been tracing the Zabbix logs and it looks like the communication between ...
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1answer
42 views

CentOS 5.10 TCP Sequence Number

We have done a security check on a server and its come back with Linux Kernel TCP Sequence Number Generation Security Weakness. We are looking to correct this being flagged up on the check We are ...
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2answers
378 views

Linux NFS hangs after about 15 minutes

I'm somewhat new when it comes to administering Linux and NFS, so please bear with me. We are trying to setup a small cluster at work. Currently the system is just 2 DELL high-end workstations, ...
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1answer
2k views

Linux Kernel complaining about TSC when selected clock source is Hyper V

We are running RHEL 6 boxes on HyperV with Windows Server 2012. On a few on our RHEL boxes, I am seeing this error in /var/log/messages kernel: Clocksource tsc unstable (delta = -62519781 ns). ...
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2answers
616 views

Linux: echo 3 > /proc/sys/vm/drop_caches takes hours to complete

I have a Thecus N8900 NAS, which is a Linux based file server, providing files via NFS to six clients. For some reason that Thecus support has yet to explain, it runs a script that checks ...
4
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1answer
710 views

linux initcwnd and initrwnd via /etc/sysctl.conf

Folks, As we know, the 3.x kernels have higher TCP default connection values, such as initcwnd and initrwnd. For 2.x friends, is there a way to set these in /etc/sysctl.conf instead of the ip route ...
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1answer
86 views

Can high disk cache usage lead to external fragmentation and ultimately to page allocation failures?

We're getting page allocation failures on a Linux server (3.2 kernel). We've been told the problem is directly related to the high use of the memory for cache; this would lead to external ...
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2answers
156 views

All terminal windows suddenly disappear in Linux [closed]

Sorry in advance for the wall of text. I'm having a problem which is leaving me with very few clues as to what might be going on. Also, I apologize if ServerFault isn't the ideal place for this ...
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37 views

Upgrading to PAE Kernel

I have Fedora 15 running in a box with 8GB ram and a 32 bit kernel; I would like to make use of the entire RAM real estate by upgrading to a PAE Kernel; however the machine is in a remote location and ...
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117 views

zeroshell unsupported onboard Intel Ethernet I217-V and I210

I recently installed zeroshell 3.0.0 on a machine with a supermicro motherboard that has 2 onboard ethernet cards. It seems that this version of ZS does not support both of ethernet. I've read from ...
4
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1answer
180 views

CVE-2014-0196 Vulnerability for CentOS

Trying to patch CVE-2014-0196 Vulnerability but yum can't find packages updates CentOS 6.5 (Final) Panel version: 11.0.9 Update #61 # uname -r 2.6.32-358.11.1.el6.x86_64 # yum update kernel Loaded ...
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2answers
588 views

ext3/ext4 physical block size view

I'm using a suse 11 server with xfs and using "xfs_info /srv" command i seen this. xfs_info /srv/ meta-data=/dev/mapper/vg01-srvvol isize=256 agcount=38, agsize=1964032 blks = ...
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0answers
78 views

Cassandra hangs with kernel exception when adding jna jar to classpath

I have a fresh installation of cassandra v2.0.8 on a RedHat Enterprise Linux v5. I have added a sym link of the jna.jar in cassandra's /lib folder. I start cassandra and it hangs after printing out ...
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1answer
54 views

“sock_sendmsg-error 22” error in RHEL

I am using RHEL 5.10 servers ( which are in cluster using some shared services). When I restart them using "init 6" or "reboot". the servers hang while shutting down, continuously showing the below ...