The performance tag has no wiki summary.
2
votes
1answer
406 views
Linux disk I/O performance issue — what config options to look at?
We discovered an I/O related performance problem when using the default SLES11 SP2 kernel. Our same application on the same hardware had no issue with (the admittedly ancient SLES9 SP3).
We had a ...
2
votes
2answers
578 views
slow media - disk cache tuning?
Is there any way to make the system more consistent when using LUKS? (or slow storage in general) as it is everything is snappy until the write buffer is full, then everything grinds to a halt as the ...
0
votes
1answer
31 views
udevadm slow boot
After I upgraded from Slackware 13.70 to 14.0, when the machine is booting, it takes it 15 seconds to execute this line:
/sbin/udevadm trigger --action=add
I understand, that it tries to detect ...
4
votes
2answers
247 views
Replace require statements by autoload in .emacs file to improve performance
According to these posts:
How can I make emacs start-up faster
a-nickels-worth.blogspot.de/effective emacs
one can somehow replace require and load statements in the .emacs file to speed up the ...
3
votes
2answers
63 views
CPU usage of KVM
I have a linux host with 4 KVM linux guests. All the guest are pretty much idle, having a load of <0.1 inside the guest.
Now, if I do a top on the host, each KVM process is using something about ...
8
votes
2answers
1k views
Heavy write activity on SSD nukes system performance
I've noticed that when I do heavy write applications, the whole system slows down. To test this further I ran this to do a (relatively) low-CPU, high disk activity:
john -incremental > file_on_SSD
...
4
votes
1answer
443 views
“Split I/O”s on a Linux VM, disk alignment
I'm trying to figure out if there's some way I can tell if a system is being adversely affected by disk misalignment -- i.e. when I do a disk I/O operation, it actually needs to request extra blocks ...
4
votes
5answers
3k views
Why is this network connection so slow?
I am having some problems with network performance speed on a Linux server running Ubuntu 9.10. Transfer speeds on all types of traffic are around 1.5MB/s on a 1000mbit/s wired ethernet connection. ...
3
votes
2answers
140 views
rsyslog drops messages excessively
We have a CentOS machine acting as our syslog server. I recently noticed that the machine has been dropping large numbers of syslog messages at times. We have over 250 routers and switches, as well ...
2
votes
1answer
369 views
What could cause a NAS mount to respond slowly?
I've a directory on a NAS mount (from NetApp), that contains ~6300 image files, total size of this directory is ~ 300 MB. I get two different performances of time ls:
First time (or after waiting 5-7 ...
6
votes
5answers
330 views
Processor usage increases with 4GB RAM installed
I have an Intel Atom D2700 (Synology NAS DS412+) with 4GB RAM running kernel 3.2.30 x86_64. This unit has a single DIMM slot.
One thing I, and other's have found, is that when adding a 4GB DIMM ...
3
votes
1answer
46 views
How does irqbalance determine which package to use?
irqbalance --debug shows the following:
Package 0: Core 0, 2, 4, 6, 8, 10, 12, 14
Package 1: Core 1, 3, 5, 7, 9, 11, 13
When I run network applications, it seems like IRQs are being handled by ...
1
vote
2answers
71 views
why is filesystem intensive script not faster on ram disk
I have a script which creates a lot of files and directories. The script does black box tests for a program which works with a lot of files and directories. The test count grew and the tests were ...
17
votes
6answers
3k views
Force directory to always be in cache
I've been testing out different methods to improve the time it takes to compile my entire c++ project. Currently it takes ~5 minutes. I experimented with distcc, ccache, and others. Recently, I ...
2
votes
1answer
81 views
Does encrypting my whole Lubuntu slow running programs down?
During the installation of Lubuntu I chose to encrypt my whole HDD (not just the /home folder). Now it feels like my system has slowed down a lot. Especially the startup time of programs increased.
...
2
votes
1answer
135 views
Best way to encrypt my system on an ssd
I consider to buy an ssd for my laptop (something like Samsung 830 or 840) to make the system more responsive. I want my system (at least my home partition) to be encrypted. However I know about ...
0
votes
1answer
54 views
Open screen in terminal after user login [duplicate]
When a user logins to my Debian server using e.g. Putty, I need to perform the following:
It will automatically execute command screen -r MyWindow, and
the user won't be able to leave the screen ...
4
votes
1answer
143 views
Linux mutex spins [closed]
On Solaris I can use mpstat to see the smtx (i.e., spins on mutex or in other words locks not acquired on the first try) value. This value increasing indicates that swap is being hit too frequently ...
4
votes
1answer
73 views
Determining LVM Extent numbers for given file
I'm currently engaged in a non-work related homework exercise. I have an ext4 filesystem sitting on a logical volume. I'm testing different performance tuning strategies and this idea occurred to me. ...
1
vote
1answer
50 views
Establishing I/O Patterns for an Application
Are there any system tools that allow you to profile an application's usage of storage? Basically, I'm looking for information on determining whether there are more large sequential reads, tiny ...
0
votes
1answer
36 views
USB Drive Software Disk Mirroring - Is this the right approach?
I have a 1TB NTFS USB Data Drive (no boot, etc...) that I would like to keep a mirror of as a backup in case of hardware failure.
It is always connected to my raspberry pi running the raspbian ...
10
votes
1answer
476 views
How do I go about tracking down IO usage in Linux and other *nix OS'?
Occasionally, something on my system starts hammering the disk. I would like to log data that would let me know about I/O usage per process, then I could go back to it later and see what keeps doing ...
2
votes
4answers
110 views
Grep of many keywords over many files: speeding it up
I am currently facing a "performance problem" while using grep. I am trying to locate the occurrences of many (10,000+) keywords in many (think Linux kernel repository size) files.
The objective is to ...
0
votes
0answers
113 views
NFS server optimization for maximum performance
I'm looking for maximum of performance for a NFS mount.
I'm on local network, it could be completly unsecure, the performance is the most important in my case.
What I already found :
In /etc/export ...
2
votes
2answers
419 views
vmstat IO stats: why the high bo during a download?
On my RHEL 4 machine, I was downloading a huge file (2.5GB)..I was checking the output of vmstat and was especially curious about seeing the disk IO using bi and bo. I know iostat is a better tool ...
7
votes
3answers
3k views
Why is kworker consuming so many resources on Linux 3.0.0-12-server?
Last Friday I upgraded my Ubuntu server to 11.10, which now runs with a 3.0.0-12-server kernel. Since then the overall performance has dropped dramatically. Before the upgrade the system load was ...
2
votes
1answer
147 views
Huge page and performance improvemnt
How can using huge page improve performance?
I have read that huge pages improve performance by reducing TLB lookups and reducing the size of the page table. Can someone tell me how this helps with ...
17
votes
2answers
508 views
Should I care about unnecessary cats?
A lot of command-line utilities can take their input either from a pipe or as a filename argument. For long shell scripts, I find starting the chain off with a cat makes it more readable, especially ...
3
votes
2answers
138 views
Is there any performance penalty to having multiple segments for one volume in LVM?
We have a big drive that we've split up using LVM. We allocated one segment to the root filesystem and several other segments to other filesystems. Then we wanted to add more space to the root ...
4
votes
2answers
2k views
Diffing two big text files
I have two big files (6GB each). They are unsorted, with linefeeds (\n) as separators. How can I diff them? It should take under 24h.
1
vote
1answer
72 views
Speeding a find rm command with test through parallelization
I want to recursively delete all files in directories and subdirectories with number of lines less than 10, and am currently using the following command
find . -type f -name "*.txt" | while read; do ...
3
votes
1answer
234 views
Measure hard-disk read(), write() speed without caching in QNX 6.5
I am working on QNX 6.5 Operating system. QNX 6.5 supports POSIX APIs. I am trying to build an application which is used to evaluate performance of hard-disks. My application will read/write/read ...
1
vote
1answer
102 views
vmstat on virtual machine and large values
Hi I'm using vmstat to track machine performance during some tests (jmeter).
This is virtual machine running on a big machine where lots of other virtual machines are installed (about 20 virtual ...
2
votes
2answers
413 views
Performance virtualbox diskfiles vs rawdisk
Pros and cons with this two ways to make disk for virtual machines on virtualbox
$ vboxmanage createhd --format VDI --size ${SIZE} --filename /path/to/disk.vdi
and
# vboxmanage createrawvmdk ...
0
votes
2answers
253 views
btrfs performance
I decided to mess around with btrfs and found some weird performance anomalies. The tests I've done are with with two external hard drives one formatted with ext4 the other btrfs.
ext4 performance ...
1
vote
1answer
78 views
How to configure Linux to run benchmarks as stable as possible?
I have several long running benchmarks (SPEC CPU 2006 benchmarks) to run on a Linux server.
The server is running Gentoo Linux with a Linux Kernel 3.6.11.
I saw some big differences between ...
2
votes
1answer
123 views
Why is connecting to Oracle Express 11 is very slow on Fedora 17?
I installed oracle-xe-11.2.0-1.0.x86_64.rpm on Fedora 17-64-bit. I was wondering why it is very slow, for example when I want to connect to it using Oracle SQL Developer or JDBC in my web application.
...
13
votes
2answers
3k views
Why does high disk I/O reduce system responsiveness/performance?
I never quite understood why high disk I/O slowed the system so much. It's strange to me because I would expect the slow-down to affect only those processes dependent on the hard/optical drive data, ...
0
votes
1answer
170 views
Rygel slowing down my Debian system
Recently I noticed that a process called rygel is taking a lot of IO resources every time I am starting something on my home system. What is this process doing and how can I disable it?
2
votes
0answers
161 views
Local disc copy at 10MB/s! What could be the problem?
I am running a Debian 6.0.6 (before you ask). I have a regular desktop computer, nothing fancy... but when I copy a file using nautilus I am getting 10MB/s copy speed and the system is completely ...
1
vote
2answers
80 views
When all hardware resources are free what would cause linux to run slowly
Sometimes, after a few hours, my system works slowly. I have checked status of these resources:
Hard disk using iotop
Ram usage using free
CPU usage using top
None of them are busy. top also shows ...
2
votes
1answer
98 views
Alix Board write performance
I have an alix board on which I have installed debian4alix (sqeeze). After using it for a while I noticed that the write performance of the board was pretty low.
I ran the following test:
dd ...
61
votes
7answers
9k views
Why use swap when there is more than enough RAM
Using swap space instead of RAM can drastically slow down a pc.
So why, when I have more than enough RAM available, does my Linux system (Arch) use the swap?
Checkout my conky output below:
...
2
votes
1answer
459 views
Is it possible to trigger OOM-killer on forced swapping?
Is it possible to have the system preemptively swap out inactive pages (vm.swappiness), but invoke the oom-killer when the system runs out of RAM (as opposed to running out of memory) and is forced to ...
4
votes
2answers
304 views
Linux (3.4) SSD swap partition usage causes extreme latency - how to eliminate?
I'm running on 4G RAM with an extra 6G swap partition, SSD is a pretty decent SAMSUNG MZMPA128HMFU model. System responds very well to workloads when things stay in RAM, but as soon as things reach ...
6
votes
1answer
241 views
echo vs <<<, or Useless Use of echo in Bash Award?
By now the Useless Use of cat Award is very well known, and there's also a mention of a Useless Use of echo (not relevant for this question). I'm wondering if there should be a "Useless Use of echo in ...
3
votes
2answers
607 views
Optimal SSD configuration
I am thinking about buying an SSD for my Debian system. However, because I don't know what is the optimal arrangement (i.e. what goes on the SSD), I am not sure what is the optimal size. Obviously I ...
0
votes
1answer
335 views
Console CPU utilisation chart
I need to monitor CPU and network utilisation from a terminal.
For network traffic, I have found the perfect tool:
slurm
It gives me a moving chart. It gives me an nCurses-like UI I can use from ...
3
votes
1answer
410 views
What settings can I use to maximize FFMpeg performance?
I'm trying to do some screencasting, but since my computer is much too old and slow the video being produced is laggy and the application I'm trying to record becomes unresponsive due to the CPU ...
2
votes
0answers
294 views
Send print job to printer immediately without queueing, aka increase print performance
I have a ruby/rails web application, one action of which sends PDF files that have been generated by the app to a Xerox 4127 printer on the network. This is accomplished via shelling out and running ...
