The speed at which a program runs

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822 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 ...
4
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3answers
312 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
37 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
225 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
335 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
119 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 ...
3
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1answer
44 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 ...
3
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3answers
251 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
162 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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0answers
190 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 ...
0
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1answer
35 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
141 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
11 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
80 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 ...
0
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1answer
65 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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0answers
46 views

How can I profile/benchmark RAM performance?

I would like to know if my memory hardware is a bottleneck of my system performance. I am dealing with really old hardware (late 2000). If there is room for improvement, I would like to upgrade. ...
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2answers
140 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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0answers
57 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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1answer
168 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: ...
0
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1answer
130 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
201 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?
3
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3answers
478 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 ...
0
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1answer
77 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 ...
1
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1answer
291 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
166 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
604 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
2k 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
348 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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0answers
96 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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0answers
31 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 ...
0
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1answer
487 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 ...
5
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3answers
502 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
88 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
72 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
110 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 ...
5
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1answer
789 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
1k 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
22 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 ...
1
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3answers
118 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?
0
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1answer
44 views

How many interrupts and context switches good for the server?

Munin has chart 'interrupts and context switches on the system'. As far as this is a monitoring tool I assume these values are important for the server performance. So, the question is: how can I ...
0
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2answers
89 views

Analyse high load root cause

This is a cents 5.7 32bit VM running inside a vmware 5.5. host. I see high values of load average with low CPU usage. The VM has 4 vCPU’s and load sometimes reach 20. When I run vmstat I see high ...
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0answers
124 views

Isolating some CPU cores reduce average CPU usage of game servers

Hardware: FX8320 (8 cores) @ 4.4GHz, 16GB I run 10 TF2 game servers. Few days ago I isolated some CPU cores with line in linux grub config: isolcpus=5-7 The strange thing - individual CPU cores ...
1
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1answer
56 views

Does orca + RICHPse work on Solaris Containers or local zones?

I have just attempted to get RICHPse version 3.4 running on a Solaris version 10 Sun M5000. It seems to run on the global zone but not on the local zones. On the local zones RICHPse just fails ...
1
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1answer
151 views

Will SSD swap improve performance?

I am wondering if i have only 4GB ram and somehow(virtualbox,browser) isn't enough and i cannot proceed to upgrade(due to ultrabook and soldered memory) will swap held in SSD help the overall ...
0
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1answer
157 views

How does the proc/diskstats work to present that values? And for proc/stat and meminfo?

I am trying to get the diskstats data by same way that the file does. Is there any way to reach that values without reading that file? How the values are placed there? Is there any ".c" file that ...
0
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0answers
117 views

Transmission in idle or slow speed

I am running Transmission on Raspbian via the command line. transmission-daemon is running fine as well as downloading. However after the download is finished and seeding should start, the Raspberry ...
2
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1answer
159 views

How to track down the source of I/O spikes?

I am using Linux as a desktop, and keep getting seemingly random I/O Spikes. The machine becomes unusably slow. At first I thought it was just that I don't have enough memory. But looking at the ...
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2answers
83 views

Congestion Control algorithm performance testing in FreeBSD

I am working on implementation of a proposed modification of TCP Congestion Control algorithm that would allow to improve it (the CC) by adding a dynamic bandwidth estimation. I have been able (with ...
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2answers
176 views

Make rsync move (not copy) files on local file system

Can I make rsync to move large amount of files instead of copying them when on local filesystem? I would like it to behave like improved mv command. I know about --remove-source-files option but ...
6
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2answers
138 views

Besides cache, what does the Linux kernel use significant amounts of memory for?

My computer feels really sluggish. According to free, I have only ~200M RAM left and more than a gigabyte had to be swapped out. I know that it is good if memory is used for caching but this looks ...