1
vote
2answers
47 views

CentOS 6 - Kernel 3 from CentOS 7 Repo?

i want to run kernel 3 on centos 6. I found out, that it cant get installed over yum and i would need to compile it by my own. My question: Could i use the centos 7 repo to install kernel 3.x from ...
6
votes
0answers
145 views

Linux kernel 3.10.0-123.4.2 processes [flush] aren't present [migrated]

I am using CentOS 7 with "3.10.0-123.4.2.el7.x86_64" version, but I don't know why the kernel threads named flush aren't present in this kernel version. I tried to look in the kernel change log, but ...
-1
votes
1answer
25 views

Can you use CGroups inside an OpenVZ Container?

just a quick question, which i have had trouble finding the answer to: The OpenVZ Authors have been contributing a large amount of code to the linux kernel, in order to get virtualization features ...
3
votes
1answer
49 views

Kernel Compile crashing on Hyper-V due to memory issues

This is on a Hyper-V machine. I've set the min RAM to 512 and the max to 2048. The host machine has more then enough RAM. Does Linux have an issue with Dynamic RAM on Hyper-V? I can't seem to ...
1
vote
0answers
30 views

OpenVZ - updating kernel and all containers

Last night I upgraded to the latest kernel of openvz. I rebooted the host node. It came up with the latest kernel. However, the containers are still running the old kernel. What I did on the host ...
2
votes
1answer
134 views

Linux read disk cache and NFS

I am interested in the impact of the read disk cache on accessing a file through NFS. Lets say I have a file on NFS. I access it (do "cat myfile") from a linux host "A". If there's enough RAM a file ...
1
vote
3answers
485 views

Error installing new OpenVZ kernel

Seem to have an error when updating the kernel on a OpenVZ server when running "yum update" im getting the below Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: ...
0
votes
1answer
63 views

Healthy Linux machine immediately went down

This is the last log entry in /var/log/messages and after this the machine has been stopped. How can I debug why the machine has been stopped? I am not sure but maybe the system stops comes from the ...
12
votes
2answers
443 views

Kernel stack trace to source code lines

Given a kernel stack trace as below, how do you determine the specific line of code where the issue occurred? kernel: [<ffffffff80009a14>] __link_path_walk+0x173/0xfb9 kernel: ...
2
votes
1answer
171 views

Is it possible to configure the Linux kernel I/O scheduler for an NFS mount?

On a normal block device you can change the i/o scheduler like this: # cat /sys/block/hda/queue/scheduler noop anticipatory deadline [cfq] # echo anticipatory > /sys/block/hda/queue/scheduler # ...
0
votes
0answers
18 views

collect previous kernel logs in linux after reboot

how to collect previous kernel logs in linux after reboot and how to search the old logs? Initially when system is rebooted the logs are not captured and found rest of the log's.But there is an error ...
0
votes
1answer
66 views

Initrd and Initramfs

I have read about the differences between the two from stackoverflow. But I am still finding it difficult to understand tmpfs and the real advantages of initramfs over initrd. I find that on RedHat ...
1
vote
0answers
23 views

Kernel Compiling from Vanilla to several machines

When compiling kernels for machines is there a safe or correct way to create a template for say servers? I work with a lot of RHEL servers and want to compile them with GRSEC. However, I do not wish ...
2
votes
0answers
140 views

Linux cgroups cpuset w/ subs causes cgconfig not to start

I am having a problem trying to separate 2 groups using cpuset subsystem. This works fine, however if i go to add a subgroup to that group (in this case -- user1), cgconfig will fail to start with ...
-1
votes
1answer
856 views

Server freeze with “rcu_sched detected stalls on CPUs/tasks”

My web server is crashing several times a week. I see errors in syslog but I can't find a solution. I tried changing kernel to older or newer versions but no difference. I moved everything to a new ...
1
vote
0answers
64 views

Linux kernel module “Unknown parameter” stops module from loading. How to load module anyway?

The following is happening on a Ubuntu 10.04 system I'm working on: The kernel is shipped with e1000 driver module version 7.3.21-k5-NAPI. This version of the module is causing problems. To fix, the ...
0
votes
1answer
31 views

Error during the kernel booting

After kernel update I've got a problem with booting linux, does anyone know how to fix this problem ?? I am pretty sure that everything was OK during kernel compilation. Here is a picture with the ...
0
votes
3answers
192 views

Yum update problems on AWS with missing requirements and duplicate sendmail

I am running an AWS VM and tried: sudo yum update Result: Error: Protected multilib versions: sendmail-8.14.4-8.12.amzn1.x86_64 != sendmail-8.14.4-7.9.amzn1.i386 You could try using ...
4
votes
1answer
311 views

How to check if a process is non-blocking in linux without using a stack tracer?

A multi-cpu server is running several processes. One process has a thread that should always be in a spinning state, using 100% of the CPU it's been assigned. My current method (besides asking the ...
0
votes
1answer
29 views

In sysctl.conf settings, what is the difference between 'all' & 'default'?

In context of sysctl.conf settings, what is the difference between (all vs. default) like net.ipv4.conf.all.accept_source_route & net.ipv4.conf.default.accept_source_route in sysctl settings ? ...
0
votes
0answers
98 views

demonstrate Automatic Hardware Clock Synchronization By the Kernel (11 minute mode) without ntpd

From the man page of hwclock: This mode (we'll call it "11 minute mode") is off until something turns it on. The ntp daemon xntpd is one thing that turns it on. You can Ok, I have a ...
0
votes
1answer
85 views

/proc/self/mountinfo per-mount-options vs per-super-options

I am trying to check for the current status of a mounted partition, rw/ro. On Cent6 /proc/self/mountinfo has some interesting info. One of the items contained in the output for each mount point is ...
3
votes
1answer
2k views

Centos 6.5 crashing with kernel panics

I recently built a small cluster for running Solr. The cluster consists of 12 Supermicro Blades running E3-1270V2 with 32GB of ram. 11 of these servers are running fine. One of them crashes on me ...
1
vote
2answers
77 views

/sys/kernel/debug/tracing/per_cpu shows way more cpus than I have

I have 8 logical CPUs in my linux box. (As seen from /proc/cpuinfo). When I look in /sys/kernel/debug/tracing/per_cpu it shows 32 CPUs. Why the difference? If it matters, I have hyperthreading ...
0
votes
1answer
45 views

packaging current linux kernel as a rpm

I have just built a custom kernel from source (obtained from kernel.org). I can boot from it fine on my local box. I now want to make it easy for a colleague to try this kernel out. Is there an easy ...
2
votes
1answer
467 views

“kernel: Cannot read proc file system: 1 - Operation not permitted” — millions of such messages each minute in kern.log on OpenVZ VPS? [closed]

I'm seeing repeated never ending such messages in kern.log on my OpenVZ ubuntu 12.04 server. Mar 2 06:23:33 localhost kernel: Cannot read proc file system: 1 - Operation not permitted. Mar 2 ...
4
votes
1answer
849 views

What is creating the generated/autoconf.h?

We're trying to build a piece of software that demands the kernel source, not just the headers. So we downloaded the kernel source via the centos src rpm. However the autoconf.h is missing. We tried ...
0
votes
2answers
324 views

Server shutting down for no reason, kernel errors. Please advice [closed]

My server has being shutting down by itself for the last 3 days after a power related problem. It's a KVM virtual machine. It stays on for no longer than about 20 minutes then it turns off. Note that ...
0
votes
1answer
195 views

arpd does not send ARP requests

Sometimes a botnet (or whatever) tries to port scan pretty much all IPs in the internal network (two /21 subnets) in one second. As a result the router sends out a lot of ARP requests and some slower ...
1
vote
1answer
216 views

Why Kernel Low memory zone is less then 896 MB?

In my system Lowmem of kernel (NORMALZONE) is 597424 kb length. As far as I learn, it should be about 890 MB at max. Why this system uses ~590 MB? Is it tunable? I a asking this because, I'am facing ...
3
votes
1answer
1k views

How to find out the reason(s) why the network interface is dropping packets?

Is there a way on Linux to get statistics about the various reasons packets were dropped? On all network interfaces (openSUSE 12.3) on several servers, ifconfig and netstat -i are reporting dropped ...
0
votes
0answers
145 views

Error: NETDEV WATCHDOG: eth0 (igb): transmit queue 2 timed out

Today, suddenly one of the network interface went down with kernel log saying: [5859423.746817] NETDEV WATCHDOG: eth0 (igb): [5859423.746818] Modules linked in: ipmi_si [5859423.746842] Pid: 0, comm: ...
3
votes
1answer
70 views

Avoid recompiling kernel modules when updating a kernel package

I currently maintain a bunch of kernel modules on my CentOS-6-like system. Suppose I want to recompile the same kernel version (Currently 3.4.56-1) to enable CONFIG_VM_EVENT_COUNTERS (or another ...
5
votes
1answer
179 views

Linux Kernel lowmem usage

I am debugging an issue where we are running out of kernel low memory and I am trying to identify who is using the kernel low memory thats contributing to the problem. Following is the meminfo ...
5
votes
1answer
613 views

Linux arp cache timeout values

I'm trying to configure sane values for the Linux kernel arp cache timeout, but I can't find a detailed explanation as to how they work anywhere. Even the kernel.org documentation doesn't give a good ...
-1
votes
1answer
50 views

Differences between UNIX and Linux Drivers [closed]

I've been trying to find an answer to this, been on a wild goose chase. Since UNIX and Linux have different system architectures. My question is on the differences between the drivers for the SPARC ...
0
votes
1answer
1k views

Why is Linux choosing the wrong source ip address

and what to do to let it choose the right one? This all happens inside an OpenVZ container: The Host is Debian/Wheezy with Redhat/OpenVZ Kernel: root@mycl2:~# uname -a Linux mycl2 ...
2
votes
1answer
217 views

Idera ServerBackup / R1soft Kernel Modules

We currently have virtual (xen) servers from a host here in the UK and back up to an Idera R1Soft / ServerBackup system in the US. One of our servers absolutely refuses to compile the kernel module. ...
2
votes
1answer
83 views

How to tell which device in /dev a kernel module added?

I have just compiled the QLogic qla2xxx FC driver on a CentOS6.4 host, and done echo 'alias scsi_hostadapter qla2xxx' >> /etc/modprobe.d/modprobe.conf cd /boot cp initramfs-$(uname -r).img ...
0
votes
1answer
140 views

Server hangs after typing reboot command

I have a Debian Wheezy installation with Xen in kernel. All is fine but ... when I type a reboot command or shutdown -r now, my server is stuck and I see only that info on screen: INFO: task ...
5
votes
2answers
351 views

Optimal kernel configuration and patches for KVM host

I have a server (single socket Nehalem w/ 24GB RAM) acting primarily as a KVM host containing a bunch of Windows Servers and a few (tickless) Linux instances. I usually compile my desktop kernels ...
3
votes
1answer
218 views

What does nf_conntrack.acct really do?

I've found the kernel parameter nf_conntrack.acct interesting, in that the kernel documentation merely says "Enable connection tracking flow accounting". I've appended this to grub and rebooted and I ...
8
votes
2answers
380 views

Why “lsmod | wc -l” not equal “ls /sys/module | wc -l”

Why do these two commands return different results? lsmod | wc -l 100 ls /sys/module | wc -l 138
9
votes
1answer
3k views

Unexpectedly shrunk window

I run a major media upload/download site and I noticed these: Is this serious or background noise due to the big file sizes and is there any tweaks I can add to /etc/sysctl.conf to improve and ...
1
vote
3answers
379 views

High CPU usage in random IP/Port UDP DDoS

I have been getting these UDP floods with random IPs and ports. randomip:randomport -> myip:randomport 0 byte payload For some reason it is using a lot of CPU. Here is the results of perf top -e ...
0
votes
1answer
322 views

What kernel module to compile for getting QOS service on Linux

We are developing on Linux system whose kernel had been compiled without QOS service years ago. Currently we want the QOS service back and plan to compile only the QOS-related kernel modules and ...
0
votes
1answer
87 views

Open the Linux QOS Service dynamically

We are developing a C++ application on Fedora (of kernel 2.6.9). This application will use the Linux TC utility to limit the bandwidth of specific applications by scanning their ports and setting ...
2
votes
0answers
109 views

Redhat 6.4 configured to log Martian packets but is not logging ll header

I am trying to investigate the source of martian packets I have been seeing on several servers connected to the same subnet. The logging of martian packets has been enabled in /etc/sysctl.conf. ...
0
votes
1answer
99 views

Xen: what are domU kernel config requirements for live migration?

We recently added iSCSI storage to two Xen servers running a mix of Gentoo and Ubuntu 10.04 and 12.04 domUs. When trying out live migration of domU I found that I can migrate just fine the Ubuntu ones ...
0
votes
2answers
89 views

continous kernel EIP errors

I am getting the following error time to time. Process is different at each time. What do you think about the error? What do you suggest? Kernel is Linux version 3.5.3 (developer@devel) (gcc ...