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Questions tagged [linux-kernel]

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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.

601 questions
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62 votes
12 answers
269k views

Hot swapping out a failed SATA /dev/sda drive worked fine, but when I went to swap in a new drive, it wasn't recognized: [root@fs-2 ~]# tail -18 /var/log/messages May 5 16:54:35 fs-2 kernel: ata1: ...
Philip Durbin's user avatar
  • 1,671
47 votes
2 answers
65k views

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 ...
dunxd's user avatar
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43 votes
5 answers
14k views

Is there anyway, with Linux, to purposely cause a block device to report an I/O error, or possibly simulate one for testing purposes?
Dok's user avatar
  • 1,168
37 votes
5 answers
14k views

Let's say we're using ext4 (with dir_index enabled) to host around 3M files (with an average of 750KB size) and we need to decide what folder scheme we're going to use. In the first solution, we ...
Leandro Moreira's user avatar
  • 619
25 votes
9 answers
24k views

I have an application writing to an ext3 directory which over time has grown to roughly three million files. Needless to say, reading the file listing of this directory is unbearably slow. I don't ...
knorv's user avatar
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23 votes
4 answers
33k views

Is there a way to detect memory fragmentation on Linux? This is because on some long running servers I have noticed performance degradation and only after I restart process I see better performance. I ...
Raghu's user avatar
  • 286
20 votes
9 answers
67k views

Most of the time when my computer starts to need swap, I see a massive spike in CPU usage (kswapd0 is consistently using 99%-100% CPU). According to top, the time is spent in sy (system/kernel) not wa ...
Zaz's user avatar
  • 833
20 votes
2 answers
6k views

I know wa (in top) measures the CPU time on waiting for I/O. Many articles say that. But I am confused that, based on 2 knowledge points: if a process uses a system call to read disk, the process is ...
HUA Di's user avatar
  • 303
20 votes
1 answer
29k views

What's the difference between net.core.rmem_max and the third value of net.ipv4.tcp_rmem? Which has the higher priority for tcp connections? For below two examples, what's the max buffer for tcp ...
bydsky's user avatar
  • 303
18 votes
2 answers
4k views

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. ...
pingu's user avatar
  • 181
15 votes
4 answers
44k views

I have a server running CentOS 6.2 with kernel version 2.6.32, but I need to increase my application Performance. The Kernel Version 3.4 has x32abi which can improve the performance so i want to ...
shiva's user avatar
  • 147
15 votes
3 answers
29k views

The initial TCP RTO value of 3s is too long for most LAN-based applications. How can I tune it lower? Is there a sysctl?
claymation's user avatar
  • 252
15 votes
3 answers
20k views

I am trying to improve performance on my server. I have a few processes that need low jitter (less than 10ms variance). I have a load average of 4 maximum on an i7-920 (4 physical cores, 8 with HT). ...
Bob's user avatar
  • 215
15 votes
2 answers
3k views

After a cold boot of a 6.0.8 Debian server (HP ProLiant), ntpd played havoc with system time: offset and jitter with respect to the usual and reliable reference time servers growing without limit. (...
Stefano M's user avatar
  • 313
14 votes
2 answers
62k views

I received this error while trying to tail the log of a Kubernetes pod. failed to create fsnotify watcher: too many open files
Steven's user avatar
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