The speed at which a program runs

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5 views

turbostat - how to tune to make CPU%c1 = 100

I'm using my server for low-latency trading. I'm using Low Latency Performance Tuning for Red Hat Enterprise Linux 7. It suggests to run turbostat sleep 5 command to verify that Bzy_MHz = TSC_MHz, ...
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35 views

Wanted: nonassociative array in AWK

I am looking at speeding up some code in AWK by serially processing an internal string representation instead of serially processing an array representation. (For Examples 1 and 2 below assume ...
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1answer
84 views

What's the fastest way of writing 1s to a hard disk? [duplicate]

I'm currently writing 1s to a file using the following: tr '\0' '\377' < /dev/zero > /dev/sdb But this is a really slow method when I want to fill a 500GB disk. Is there a quicker way?
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22 views

Find system idle time using any system call in microseconds

For the perf analysis and to make decision based on system and app performance I need to find the idle time of system. I want the precise value in microseconds. I know that I can get the value in ...
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3answers
57 views

Rebuild original file from diff files to save disk space

Every day 10GB text file is downloaded, the file is ~200 million lines and ~1% of the lines are changed the next day. I want to keep daily files as backup, but I'm trying to save disk space by using ...
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7 views

Install orca on redhat

Has anyone successfully installed/ran orca (a performance monitoring tool for Solaris) on Redhat? I see some old posts asking about it but there have been no responses. ...
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0answers
10 views

Calcualte the correct MBit/s in my speedtest

I know wget is usually showing the speed in a summary, but in my small OpenWRT shell. I want to test how long it takes to download 100MB with t=$(date +"%s") wget ...
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2answers
235 views

Fastest way to delete duplicates in large wordlist?

I need to deduplicate a large wordlist. I tried several commands and did some research here and here where they explain that the fastest way to deduplicate a wordlist seems to be using awk. awk ...
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1answer
111 views

How low can I go on RAM?

I have some old PCs runnning on my business. And by old I mean PENTIUM-3 800 MHZ and AMD DURON 950 MHZ, with 256MB RAM. They are running my business software today on Windows XP. I want to run Linux ...
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0answers
35 views

How does performance measurement tool 'perf' actually work?

a perf tool which accesses the performance counter registers of an machine and gives out metrcis to user to analyse the system performance what i am curious about is , when i read the parts of ...
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1answer
28 views

Python processes appearing and disappearing in top

I concurrently launched around 12 Python scripts on a 24-core server (Ubuntu 14.04 LTS x64). Each of Python script takes around one hour to complete. I see in top that they appear quite sporadically, ...
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2answers
713 views

Why I can not use all the 100% potential of CPU?

I am using my computer clusters to run a MD C program but I can not use full potential of those clusters. But the this node have 16 CPUs and I also only give 15 jobs for those CPUs. But I can not ...
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3answers
285 views

Grep all at once

The script I have receives arguments and needs to grep through another file. Script loops through every argument. Is there a way to collect the arguments in a single search string and grep with OR ? ...
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0answers
20 views

How can writing speed equal to reading's over nbd and ram disk

My testing is under two nodes whose communication is over nbd,and each node uses ram disk as local storage.The result is that reading speed can reach the bandwidth 6GB/s,while writing speed is only ...
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2answers
86 views

how to go mouseless [closed]

I would like to improve my efficiency. I recall seeing some tool to use gui applications on linux with the keyboard, but I do not recall much else about it! Please advise how I can go mouseless(for ...
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3answers
330 views

The performance difference between a command that does the same thing

What is the difference? It is performed in the same? tar -czf files/compressed/gzip/archive.tar.gz -C files/original . tar -c -C files/original . | gzip -1 > files/compressed/gzip/archive.tar.gz ...
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1answer
59 views

how to disable access time settings in Debian linux

Performance Best Practices for MongoDB implies that: Most file systems will maintain metadata for the last time a file was accessed. While this may be useful for some applications, in a ...
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1answer
31 views

Cache atime writes

Is there a way to set atime writes to be cached for a very long time? I need atime (that is to say, relatime won't cut it), but I don't want it to effect performance so much. Data loss in of atimes ...
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3answers
114 views

Linux, SSD and swap

This article suggests not to create a swap space on an SSD drive in order to reduce its wear. On the other hand, it suggested here that swap space positively affects performance. Would it be a better ...
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1answer
54 views

btrfs on LVM on LUKS - one LUKS container performs WAY better than the other

I have 2 LUKS containers, one with default OpenSUSE installer settings, another one with -h sha512 -s 512 -i 5000 and detached header. On top of each of them there is LVM - one with only 1 OS volume ...
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40 views

where to compress=lzo, btrfs with virtual disk images, with their vm's internally using btrfs

I've been using compress=lzo on my btrfs volumes, because I read this fast compression method actually increases drive performance. (Haven't tested myself.) I'm starting to use ...
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1answer
20 views

Is it possible to have some shared objects be preloaded asynchronously during boot?

If I recall correctly, the same shared object is not loaded into memory twice when it's used by multiple processes. Is it possible to have some shared objects preloaded into memory asynchronously ...
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1answer
80 views

Wordlist/dictionary generation for penetration testing

How can I generate a dictionary of words containing 8-16 of alphabet characters ([a-zA-Z]) with low memory?
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0answers
9 views

Turn off slide effect on kde menu

I have a remote computer via a nomachine connection. I use kde on the remote machine. How to turn off slide effect in KDE menu?
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1answer
50 views

Stable timing for shell scripts?

The run times of scripts vary quite much. I would like to find similar time -function as Matlab's timeit, described here. For instance, I am evaluating these commands here about counting quickly ...
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1answer
43 views

How can I track long-term system performance in Linux (Debian)?

I love the RRD graphs that pfSense provides. Is there a package for Debian or a generic tool that can do the same for my Debian box?
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18 views

How can Profile/Benchmark ram performance?

Effectively I would like to know if my memory hardware it a bottleneck of my system performance. I am dealing with really old hardware (late 2000), mind you. If there is room for improvement I would ...
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2answers
41 views

Performance of `tar -xf` (block size related)

I'm recently working on optimizing the performance of tar -xf, i.e. untar a file. I notice that under default settings, tar -xf calls writes to write 10 KiB output at a time in chunks. However, this ...
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34 views

Delaying packets with libnetfilter_queue

From my Raspberry Pi configured as an access point, I set the following rules: sudo iptables -I FORWARD -p tcp --sport 25 -j NFQUEUE --queue-num 0 sudo iptables -I FORWARD -p tcp --sport 80 -j ...
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66 views

Why is my UDP bandwidth significantly lower than TCP bandwidth in iperf

I am running a simple bandwidth test between two VMs using iperf. I am getting very different bandwidth reading for TCP and UDP where the UDP bandwidth is terribly lower than TCP. TCP: ...
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1answer
71 views

What is the impact on system performance when kernel debug info is enabled?

In order to debug kernel or use tools like stap (https://en.wikipedia.org/wiki/SystemTap) kernel must be compiled with full debugging information included - namely option CONFIG_DEBUG_INFO has to be ...
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1answer
57 views

Show CPU core usage for parent process and its child processes

Is it possible to display CPU core usage just for a single process and its child processes on Linux?
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3answers
215 views

Linux & Linux-Software: Advantages of a multi core processor [closed]

I plan to get a new notebook and try to find out if a quad-core processor gives me any advantages over a regular dual-core machine. I use common Linux Distributions (Ubuntu, Arch etc.) and mostly ...
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1answer
54 views

Relaunch an app if it freezes

Yesterday I successfully managed to make a kiosk from Ubuntu Server. I'm going to use it to rub some web application that will run non-stop. However, in some cases, duo to lot of js animation I'm ...
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1answer
161 views

Least resource-consuming Linux OS to run just Chrome

I've developed some application which uses a browser in order to run. The usage of the browser is simply for the GUI which is built with html/css/js (there are lot of js animations). Currently, the ...
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2answers
96 views

What is actually the speed reported by dd?

I always thought that when doing: dd if=/dev/sdx of=/dev/sdy the report which is displayed once the command finishes, such as: 79304319+0 records in 79304319+0 records out 40603811328 bytes (41 ...
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0answers
278 views

Linux Mint 17.1 Cinnamon is slower in computer than in Virtual Box

After some months working in a VirtualBox VM with Linux Mint (the host as a Windows 7), I've finally installed Mint 17.1 Cinnamon on the same computer. And the experience hasn't been good. The fact ...
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3answers
616 views

How to calculate the memory consumed by a “C” program in linux

I have written two C programmes one is using function pointer, and the other without function pointer. Now i want to know the memory consumed by the two programmes , to see how memory can ...
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4answers
167 views

any large inode size benefits? (ext4)

From some foggy memories I thought I would "improve" the default settings when creating a Linux partition and increased the inode size to 1024, and also turned on -O bigalloc ("This ext4 feature ...
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63 views

Disk configuration options, what can affect performance

I have 2 disks, the same model and vendor, first one , probably performs faster. We do write into multiple files. Can you compare 2 configurations and tell what can affect performance? 1. (faster) ...
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29 views

How do I gather average cpu use in the background?

I'm trying to determine if an issue I'm having is related to cpu use, but my impacted application doesn't allow me to change terminals once it's open. It there a way I could dump only the cpu useage ...
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1answer
192 views

Why and how is swap improving performance, and can I disable it? [closed]

I have a laptop with 8GB of RAM running 4.0.4-2-ARCH. Recently, I installed Android Studio, and bam, my normally pristine system was suddenly stuttering and all out freezing (more than once). Before ...
4
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3answers
385 views

On a Linux system, see how busy is file system

I want to know of a command that will show me how (currently) busy is the file system. I'm assuming there exists such a command that will show me this. With such command, are there specific arguments ...
2
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1answer
64 views

POSIX shell scripting and performance tuning [closed]

Nowadays, I'm researching for performance tuning for shell scripting , And I have been prevented to POSIX shell scripting, However it's only a standard, But I think it's rathar than standard for do ...
2
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0answers
46 views

How to use blktrace to monitor the eMMC Flash access pattern?

I'm trying to simulate a FTL(Flash Translation Layer) algorithm and evaluate its performance. What I need is a trace file of a flash access(containing information about block and page access). I'm ...
2
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1answer
50 views

What data transfer / write speeds are to be expected for a badblock destructible write test?

I have purchased a new HDD for my backups. Before entrusting the device with the job of keeping my data safe I want to make sure that it is in good condition. The drive is a new internal 3.5 inch SATA ...
4
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1answer
250 views

Abysmal general dm-crypt (LUKS) write performance

I am investigating a problem where encrypting a block device imposes a huge performance penalty when writing to it. Hours of Internet reading and experiments did not provide me with a proper ...
1
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1answer
226 views

Physical and logical extents size

I have created a partition with 36TB (/dev/sdb1) in rhel 6.6 Now I want use this for lvm What is recommended size for Physical Extents, Volume Extents and Logical Extents How important PE, VE and LE ...
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0answers
19 views

Is the perfmon2 tool obsolete due to the same functionality being included in the current Linux kernel?

I was having some issues with the PAPI tool and multiplex and this answer by the PAPI creator led me to check out perfmon2: http://lists.eecs.utk.edu/pipermail/ptools-perfapi/2008-April/000900.html ...
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3answers
90 views

Would installing a desktop enviroment slow down a server?

I would like to install Gnome Desktop with Centos7 and see how it works. Can Gnome be turned on and off when rebooting, or easily removed if needed?