The speed at which a program runs

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3
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1answer
24 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 ...
0
votes
0answers
12 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 ...
4
votes
1answer
2k views

Audio/video out of sync when playing MP4s in mplayer

When I try to play MP4 files in mplayer, after a few seconds I get the "Your system is too SLOW to play this!" warning and the video starts lagging behind the audio. It only happens with MP4s, and ...
1
vote
2answers
32 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 ...
0
votes
1answer
24 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 ...
0
votes
1answer
11 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 ...
0
votes
1answer
55 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?
1
vote
0answers
50 views

How fast is a process reading/writting virtual memory?

So, we have top, htop, iotop, iostat, vmstat, etc, to measure many different things on Linux, but how can one measure how much MB/s a process is reading and writting to/from RAM, i.e., virtual memory? ...
0
votes
1answer
284 views

Why Linux games are less performanced than Win 7?

I had Windows 7 x64 and now I have Ubuntu 14.04 on notebook HP 4535s. I expected games to be faster in Linux than on Windows because of fewer machine requirements. But it isn't so... E.g., games via ...
5
votes
5answers
3k 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?
0
votes
0answers
6 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?
2
votes
1answer
46 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
votes
3answers
3k 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 a ...
0
votes
1answer
33 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?
1
vote
1answer
36 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 ...
7
votes
2answers
12k views

rsync is very slow (factor 8 to 10) compared to cp on copying files from nfs-share to local dir

I have a freshly installed Ubuntu-server which is ought to be the new backup-server for our VM-storage. The server has 4 nics, 2 of them 10Gbit (in fact an intel x540-T2 with the newest driver ...
1
vote
0answers
14 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 ...
1
vote
1answer
25 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 ...
0
votes
0answers
24 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 ...
92
votes
7answers
31k views

Why use swap when there is more than enough free space in 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: Also, ...
4
votes
1answer
516 views

GNU/Linux, IO performance problems

I have some problems with my system performance. As I was adviced here, I used sar: $sar -u 5 and found out that the problems are caused by a low HDD performance, as I supposed (high %iowait). ...
1
vote
0answers
40 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
votes
1answer
44 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 ...
3
votes
3answers
95 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 ...
1
vote
1answer
28 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?
0
votes
1answer
44 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 ...
14
votes
3answers
426 views

What is the IPsec bottleneck in Linux?

I am trying to compare the performance of several network security protocols between two hosts connected in Gigabit Ethernet. My goal here is to see if I can saturate my bandwidth, and if not, what ...
1
vote
1answer
109 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 ...
4
votes
2answers
59 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 ...
0
votes
1answer
707 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
0answers
134 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 ...
2
votes
4answers
94 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 ...
1
vote
3answers
344 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 ...
27
votes
7answers
7k 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 ...
38
votes
4answers
18k views

Is there a way to determine the optimal value for the bs parameter to dd?

On occasion I've seen comments online along the lines of "make sure you set 'bs=' because the default value will take too long," and my own extremely-unscientific experiences of, "well that seemed to ...
4
votes
3answers
352 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 ...
1
vote
0answers
53 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) ...
0
votes
0answers
27 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
votes
1answer
84 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 ...
21
votes
3answers
3k views

Is dash or some other shell “faster” than bash?

I always thought that the only benefit of using dash instead of bash was that dash was smaller, and therefore many instances of dash would start faster at boot time. But I have done some research, ...
1
vote
1answer
38 views

Using `perf` repeatedly with file input

perf can be used to analyze the performance of a program. Say you want to test the performance of a program prgrm, with input from a file, you can run: perf stat prgrm < inp.dat Now when you ...
2
votes
1answer
55 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
votes
0answers
28 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 ...
18
votes
5answers
10k views

Is there a parallel file archiver (like tar)?

Is there something out there for parallel archiving of files? Tar is great, but I don't use tape archives, and it's more important to me that the archiving happens quickly (with compression like ...
2
votes
1answer
37 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
votes
1answer
135 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
vote
1answer
91 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 ...
1
vote
0answers
17 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
vote
3answers
75 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?
75
votes
3answers
141k 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?