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7
votes
2answers
90 views

How can other processes affect measurements made with `time`?

If I time a process using the time command, I get output for 'real', 'user', and 'sys'. My understanding from this discussion is that 'real' is wall time, whereas 'user' and 'sys' are process time. ...
1
vote
1answer
795 views

Performance of RAID 1 with 3 Disks under Linux

The standard way to setup a RAID 1 under Linux is to use two disks of the same size. The write performance is almost as good as with a single disk drive. The read performance can be up to twice the ...
1
vote
0answers
117 views

Solaris 10 on x86: local sockets (unix domain sockets) very very slow? [closed]

I'm writing an application both on Linux and Solaris 10. It uses local sockets for some internal communications. On Linux an open, exchange one short message & close cycle takes about 10us elapsed ...
0
votes
2answers
45 views

Fedora 17 Performance Issues [closed]

I have a Dell Latitude E4310. I have Windows 7 and Fedora installed on it. I rarely use windows and I have been using fedora for a good 9 months now. Recently the performance on my machine degraded ...
2
votes
2answers
3k views

Running thousands of curl background processes in parallel in bash script

I am running thounsand of curl background processes in parallel in the following bash script START=$(date +%s) for i in {1..100000} do curl -s "http://some_url_here/"$i > $i.txt& ...
3
votes
4answers
215 views

Does cron jobs per se represent a significant burden on a modern system?

I'd like to run a pretty simple script (is there a dir with name x in dir y if so move it to dir z–and x will only be there about once a day) every 15 seconds or so (one minute divided into 4*15 ...
2
votes
1answer
48 views

Multiple Lan interfaces on one VM rather than multiple VM

I'm looking if it's possible to give rights, to only allow the use of one network interface to a specific user on a Linux distribution. My use case: I want, for my studies, testing the ...
0
votes
2answers
90 views

Varing speed when reading sequentially from a HDD

I have just got a new HDD and I wanted to test the sequential read speed (the whole disk). I used: pv /dev/sda > /dev/null The disk is 500GB WD VelociRaptor (WD5000HHTZ). At the beginning the ...
0
votes
1answer
212 views

Performance Issue: AWS Medium Linux Instance V/S Hetzner Dedicated Instance

I am testing an AWS Medium Instance with CentOS (AWS AMI) and comparing it with Hetzner's EX40-SSD (http://www.hetzner.de/hosting/produkte_rootserver/ex40ssd). Software setup on both is comparable( ...
23
votes
9answers
997 views

for vs find in Bash

When looping through files there are two ways: 1. use a for-loop for f in *; do echo "$f" done 2. use find find * -prune | while read f; do echo "$f" done Assuming these two loops will ...
1
vote
1answer
197 views

Ubuntu 12.04LTS becoms slow and jerky randomly for a mintue and then becomes normal by itself [closed]

I am using Ubuntu 12.04LTS on my Toshiba satellite L510 and I have only Ubuntu installed. The system becomes slow and jerky by itself after every 10minutes or so and the remains like that for less ...
10
votes
2answers
875 views

Why is wc so slow?

Why is the wc utility so slow? When I run it on a large file, it takes about 20 times longer than md5sum: MyDesktop:/tmp$ dd if=/dev/zero bs=1024k count=1024 of=/tmp/bigfile 1024+0 records in 1024+0 ...
3
votes
3answers
283 views

Best way to benchmark different encryption solutions on my system

I want to compare different encryption solutions for encrypting my system, possibly different solutions for different parts of the system such as /usr or /home. In particular I look at dm-crypt ...
0
votes
2answers
7k views

CPU usage monitoring in AIX servers

In order to monitor the CPU usage in an AIX server I'm using the following script that is executed every 10 mins. lparstat 2 10 > cpu usage=$(tail -10 cpu | awk 'BEGIN {sum=0;} {sum+=$4} END{print ...
3
votes
1answer
471 views

Efficient way to print lines from a massive file using awk, sed, or something else? [duplicate]

If I had a plain-text file containing 8 million lines and I want to print out lines 4,000,010 to 4,000,000 to the screen, which would be more efficient: awk or sed? There is no pattern to the text, ...
4
votes
2answers
674 views

Massive, unpredictable I/O performance drop in Linux

I'm using Debian testing without any problems for ~6 years (I'm just regularly updating it), but recently it started to show a random behaviour that can be summarized as "Low I/O performance which ...
1
vote
0answers
136 views

Why does my CMS run extremely slow in my workstation (Ubuntu)

For over a year I have been struggling with the response speed on my Drupal v7.2x CMS install. Let me explain. I'm running Drupal 7.2x on an Ubuntu 12.10 (upgrade to 13.xx pending) for the purpose of ...
4
votes
2answers
4k views

Benchmark ssd on linux: How to measure the same things as crystaldiskmark does in windows

I want to benchmark a ssd (possibly with encrypted filesystems) and compare it to benchmarks done by crystaldiskmark on windows. So how can I measure approximately the same things as ...
3
votes
1answer
354 views

Rsnapshot via SSH speed issue

I am trying to backup bunch of desktops running RedHat 6.4 (i86_64) LVM on the top of ext4 to our file server running RedHat using rsnapshot and ssh. I am on 1GbE. I am finding the speed of the first ...
1
vote
0answers
95 views

Terraria Server Seems to be Slowing Down Web Server [closed]

I currently have a CentOS 6 Cloud server (2gigs of ram, 40gigs of SSD storage, 2.4ghz quad core, and 100M unmetered port for bandwidth) that has in the past run a TeamSpeak, Minecraft FTB (modded ...
4
votes
3answers
376 views

Why is bash's printf faster than /usr/bin/printf?

I have two ways of calling printf on my system: $ type -a printf printf is a shell builtin printf is /usr/bin/printf $ file /usr/bin/printf /usr/bin/printf: ELF 64-bit LSB executable, x86-64, ...
1
vote
2answers
277 views

Performance and limitations of using an X GUI remotely?

I don't really have any experience with X. It appears from what I read that X has always been built from the ground up to allow windows in the WM to be transmitting over the internet, without ...
0
votes
1answer
605 views

How can I install perf 3.4.25?

By installing perf using sudo apt-get install linux-tools-common sudo apt-get install linux-tools-3.2.0.23 gave me perf version 3.2.14 How can I install perf 3.4.25? Is it related to kernel ...
8
votes
2answers
6k views

Performance of unix sockets vs TCP ports

For example on php-fpm: #listen = 127.0.0.1:9000 listen = /var/run/php-fpm/php-fpm.sock Is there any major performance differences between using unix socket-based listeners over TCP ports? (Not ...
21
votes
3answers
4k views

grep: memory exhausted

I was doing a very simple search: grep -R Milledgeville ~/Documents And after some time this error appeared: grep: memory exhausted How can I avoid this? I have 10GB of RAM on my system and few ...
0
votes
2answers
808 views

Ubuntu is running slow

I'm not sure since when it became slow, but I think after I did apt-get update. Here's my machine details: I can see from the system monitor that the CPU is working hard specially when I run Chrome ...
1
vote
1answer
183 views

Are these throughput numbers typical for an SSD?

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sdb 19722.20 170.80 7141.60 27.80 114246.40 788.80 32.09 52.25 7.19 ...
2
votes
2answers
1k views

Any tricks to speed up sort?

For example for bzip there is pbzip, a parallel version of bzip. Is there any such parallelization tools for sort to improve performance?
31
votes
1answer
34k views

How do you empty the buffers and cache on a Linux system?

Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?
4
votes
1answer
242 views

How accurate is Conky?

I'm on Crunchbang 64 bit, Conky shows that I'm using 4% of my CPU. But I can feel the CPU burning so hot, got Spotify, Chrome and couple other apps running. On windows 7 chrome uses about half of the ...
3
votes
1answer
513 views

Linux: How to check whether a process is slowed down by other running processes

I have one process running on a RHEL 6.3 machine. Somehow this is taking a longer processing time than the same process running on another machine. How is it possible to know why this process is ...
3
votes
3answers
3k views

Grep in couple thousands files

I have directory with cca 26 000 files and I need to grep in all these files. Problem is, that I need it as fast as possible, so it's not ideal to make script where grep will take name of one file ...
2
votes
1answer
363 views

Is there any tool to view live statistics about a Radeon GPU?

I've checked out GPU usage monitoring (CUDA), but are there similar tools for AMD/ATI cards? Or kind of universal tools? I want to check out if my applications use the 256 MB of RAM of the video card ...
1
vote
1answer
308 views

numfsbufs and mount/remount of File Systems

What is the right the procedure to set the numfsbufs parameter? The current value of the parameter is 196 App_Server:>ioo -o numfsbufs numfsbufs = 196 The details of the server (prtconf ...
0
votes
1answer
658 views

What does high, low, negative and constant values from pidstat command mean?

I needed information on the following: Can you please tell me the inference for the following in terms of high, low, negative and constant values from pidstat command in Linux. kB_rd/s, kB_wr/s, ...
0
votes
1answer
105 views

Is my approach to performance testing in Linux environment correct?

I want to do performance testing in a Linux environment for a C++ application. I need to measure the CPU & Memory usage of the application. This application is a multi-threaded application. In ...
0
votes
1answer
121 views

How can I look at recent system activity to figure out what caused a huge slowdown? [closed]

I'm running CrunchBang Waldorf with OpenBox on a Lenovo e420. I made the switch from Windows a few months ago, and have had no problems with performance since then. Everything runs nice & fast. ...
1
vote
1answer
2k views

ulimit & rlimit in Linux, are they the same thing?

I see people use the terms ulimit & rlimit interchangeably, can I say they are referring to the same thing?
0
votes
0answers
204 views

X high CPU when using Java applications

Only recently, my Freemind program has become extremely sluggish and unresponsive (big lag) when moving my mind map around. I use Arch Linux with xfce4. Freemind is made with Java. If I move the mind ...
4
votes
2answers
342 views

Why do systems become slow when doing massive writes to disk?

I want to know why systems become slow when writing mass data to disk. I think that for system to become slow, there should be some issue with CPU. But write is only I/O bound. Do hardware ...
0
votes
1answer
301 views

Simple bash script taking too long to execute

I wrote the following function in my .bashrc for use instead of rm * : function re() { cp . -R /home/glset/ritwik/trash/ rm * } It works .. but it is very slow. Even for small files it takes too ...
3
votes
7answers
1k views

How can I defragment my SSD on linux?

This page demonstrates that defragmentation is beneficial for SSDs. I suppose this type of defragmentation has to be trim-aware, so as to preserve the life time of the disk. How can I do that on ...
4
votes
2answers
902 views

Inotifywait for large number of files in a directory

What I want to do is, to monitor a directory (not recursive, just one) for new files created and append those files to one single big file as they are being written. The number of files that are ...
1
vote
1answer
637 views

Measurement of free ram through /proc/meminfo with ramdisk (initrd)

I am booting a disk image via PXE, it is a full system on an initrd ramdisk. I would like to measure the actual free memory of the system (not including buffers and file system caching). I was told ...
4
votes
2answers
3k 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 ...
5
votes
2answers
2k 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 ...
3
votes
1answer
655 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 ...
2
votes
2answers
392 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 ...
2
votes
1answer
1k 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. ...
0
votes
1answer
138 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 ...