The speed at which a program runs

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1answer
118 views

Why FOSS 3d performs so badly, compared to proprietary. Trying to understand

I know this is not the best question, I'm just trying to understand what needs improvement. I just read a Phoronix article, which compared the FOSS radeon drivers a 5 years old FGLRX catalyst. As ...
4
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1answer
4k 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 ...
4
votes
2answers
171 views

check patterns that don't exist in sqlite

I explained a similar situation with plain text files on Grep huge number of patterns from huge file. Many people there said I should, so now I'm migrating my data to a sqlite database: I have a file ...
55
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5answers
34k views

Can I configure my Linux system for more aggressive file system caching?

I am neither concerned about RAM usage (as I've got enough) nor about losing data in case of an accidental shut-down (as my power is backed, the system is reliable and the data are not critical). But ...
6
votes
1answer
930 views

SysBench highlighting abysmal disk write performance on white box vs Tier1 server

Have been testing white box system with SuperMicro X8DTL motherboard with various SATA hard disks such as 7,200RPM Seagate Constellation ES and 10,000 RPM Western Digital VelociRaptor. Have tested ...
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3answers
9k views

is there an open source tool to measure cpu performance?

I have used many times ab for measuring web performance, hdparm for measuring hard disk performance and netperf for measuring network performance. But I didn't find any tools to measure cpu ...
22
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4answers
1k views

Are Linux utilities smart when running piped commands?

I was just running a few commands in a terminal and I started wondering, does Unix/Linux take shortcuts when running piped commands? For example, let's say I have a file with one million lines, the ...
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4answers
9k views

Can I access Nth line number of standard output?

Assuming a script that outputs a list of files: $> bash someScript.sh path/to/some/file path/to/the/file/i/want/to/work/with path/to/yet/another/file Now I want to have the second file-path as ...
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3answers
1k views

How to average time commands?

I am timeing some of my commands. Now to average the measures, I'd like to run and time my commands a specified number of times, and get the results with a calculated mean and standard deviation. The ...
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2answers
2k views

100.0%sy with poor disk performance

I have RHEL 5.4 kernel 2.6.18-164.el5 and I am experiencing very bad disk performance that happens randomly during working with Oracle. Nothing appears in the logs. When it happens, I see one CPU ...
18
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3answers
23k views

What is the most high-performance Linux filesystem for storing a lot of small files (HDD, not SSD)?

I have a directory tree that contains many small files, and a small number of larger files. The average size of a file is about 1 kilobyte. There are 210158 files and directories in the tree (this ...
2
votes
1answer
89 views

Access times for different partitions on same hard disk

I have partitions, /dev/sda1 and /dev/sda2. / is mounted on /dev/sda1, while all other data is on sda2 which has more size allocated to it. I want to save the virtual machine images (VirtualBox ...
6
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2answers
968 views

Poor random read SSD performance on Linux

I recently got an Intel 320-series SSD, and I am having difficulty achieving the advertised 38K IOPS for random 4K reads. Both with fio and my own hacked-together program, I am seeing around 6K IOPS. ...
2
votes
1answer
1k views

Interpreting tiobench results

I'm running tiobench on my raid1 and it gives me the following results. Why is there ##### shown instead of throughput? Why does seq.reading with 8 threads use 2836% CPU? My results: $tiobench No ...
4
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2answers
2k views

OpenBSD performance tuning (desktop)

What are your ways of tuning a freshly installed OpenBSD operating system specifically for a desktop environment (faster UI interaction etc.)? What are the most important factors here to consider?
4
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1answer
513 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). ...
4
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2answers
2k views

How to install light-weight vim and to be able to efficiently load files into one instance vim?

On my laptop with Ubuntu I'm able to have just one instance of vim, launched with vim --servername VIM After this I'm able to open files from console with vim --remote-silent filename I use ...
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4answers
13k 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 ...
11
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1answer
6k views

Using Linux cgroups to balance CPU performance

I have two dual-core Linux systems installed using Linux cgroups with relatively recent kernels; one is running Debian Squeeze, the other Ubuntu 11.04 Natty Narwhal. I've gotten CPU load balancing ...
2
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5answers
3k views

How to determine why a machine is running slowly?

I log into a linux server (installed as a virtual machine) using a graphical ssh client (securessh). This server runs a tomcat5.5 server where nexus is installed. When I type commands or delete/copy ...
23
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4answers
17k views

How to speed up X over SSH on a slow network connection?

Are there any specific recommendations on speeding up X applications over ssh on a slow network connection? In this specific case, I am accessing a server located in west coast from a laptop in east ...
1
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1answer
146 views

Fedora 8 recently extreamly slow with frequent freeze ups

Over the last few weeks my Fedora 8 machine has been running extremely slow. Applications like Firefox constantly freeze up and I am seeing sustained spikes in CPU activity while carrying out typical ...
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3answers
1k views

How to speed up my build

I am doing a build on a Linux machine with ubuntu 10.04 on it. I want to know how can I really speed up my build. I have 4 CPUs and lots of RAM. I already reniced the process group to -20. Is there ...
4
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1answer
3k views

Should I disable hyperthreading when concerned about performance of single-threaded applications?

I use a i5-2410M processor, which is setup to do hyperthreading by default on my laptop. Considering that this is a 2-core processor, this means it can do 4 threads at a time. This also means that ...
3
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1answer
2k views

LVM2 partition alignment

How to do the following with Linux tools : LVM partition alignment and alignment of partition on LVM ? What in case where I want to setup LVM partition (for "pv") and then partitions ? To be more ...
4
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1answer
592 views

Efficiency of lots of inotify watches or stat calls

I am developing software that will utilize inotify to track changes on a large amount of files (tens to hundreds of thousands of files). I have come up with these ideas: one watch per file one watch ...
1
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1answer
304 views

performance on Linux system when daisy-chaining multiple USB hard-drives on USB hubs?

What would the I/O access be like as I plug many USB drives into a Linux system with only 2 USB 2.0 ports and 1 USB 3.0 port? I expect I will have to have multiple levels of fan-out by plugging hubs ...
1
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1answer
149 views

What Linux tool will tell me if all the mounted disks share roughly the same bandwidth?

What Linux tool will tell me if all the mounted disks share roughly the same bandwidth? Can I do something like iostat for each of my /dev/sd* devices?
3
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1answer
345 views

Pluggin a bunch of USB hard drives into a Linux system?

I've got a Linux system with two USB 2.0 ports and one USB 3.0 port, and I would like to know how many USB hard drives I could plug into it. On the performance side, what would the I/O access be like ...
2
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2answers
620 views

Powerful hardware, slow Ubuntu

My computer should be able to run Ubuntu (11.04) without breaking a sweat: CPU: 2.00Ghz Core i7-2630QM RAM: 8Gb DDR3-1333 HDD: 60Gb SSD GPU: 1Gb AMD HD 6570M Swap: 2.7Gb However, opening folders ...
29
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3answers
2k 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 ...
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2answers
884 views

Finding MFLOPS using Linux

How can I find out the Mflops on my linux computer? I can see the bogomips on my /proc/cpuinfo but I don't see any Mflops on that file: $ cat /proc/cpuinfo | grep -ie mips -ie flops bogomips : ...
5
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1answer
2k views

Why Process CPU % Usage larger than Total CPU Time

When I run the TOP command, a process shows 1208% cpu usage and the total CPU usr time is 81.7% with IRIX mode on. When I change to IRIX mode off, the process shows 99% cpu usage and the total user ...
2
votes
2answers
4k views

fastest way of doing a tar.gz from a tree of directories?

I've got a tree of directories with files like this: . |-- 00 | |-- 00 | | |-- 00 | | |-- 01 | | |-- 02 | | |-- 03 | | |-- 04 | | |-- 05 [..] | | |-- 97 | | |-- 98 ...
23
votes
4answers
2k views

How to limit resource usage to save CPU+RAM for a certain process?

I have a dev server on which sshd sometimes stops working because the machine runs out of RAM. Yes we are running low on memory and upgrading is not a feasible choice right now. What I want to do is ...
4
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1answer
1k views

How can I configure fair bandwidth sharing between cgroups?

It's fairly easy to use tc with Stochastic Fairness Queueing (SFQ) to configure fair bandwidth sharing between flows, but an application can open multiple flows and get an unfair share of bandwidth. ...
0
votes
1answer
284 views

How to test the difference between using disk encryption or not?

If I have a laptop, and I want to install an Ubuntu 11.04 on it, but disk performance would be an important thing, then how could I test the real differences between: - not using encryption - ...
6
votes
2answers
3k views

dd if=/dev/random is 'randomly' bottlenecked with BIG time lags, but I have no idea why

I get wildly different real times when I run the following command. dd if=/dev/random bs=1k count=1 It doesn' happen for if=/dev/null, nor does it happen for if=/dev/urandom I've run it 500 ...
5
votes
3answers
624 views

Really light weight linux for VM no extensions

I need to host a ssh server on a x86-64 Debian squeeze machine with no VT-extensions :( I am using virtlib with qemu (set up and working). I have tried a number of things and non have been perfect, ...
26
votes
1answer
2k views

Why does “ls *” take so much longer than “ls”?

I have a couple of files in a directory: $ ls | wc -l 9376 Can anybody explain why there is such a huge time difference in using ls * and ls? $ time ls > /dev/null real 0m0.118s user ...
4
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3answers
910 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 ...
5
votes
2answers
3k views

Hight iowait while the wMB/s is low

I was indexing a MySQL table. It makes a high load on that computer. It seems due to a high iowait. But it also shows that the wMB/s is only 2.87. Isn't even a common SATA HDD able to handle more ...
2
votes
1answer
1k views

mount.cifs is slow

Using mount.cifs on openSUSE 11.3, I'm getting very slow performance on a gigabit network, usually around 4-5MB/s. The following mount command has yielded me the best performance so far: mount.cifs ...
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 ...
4
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1answer
1k views

How can we customize linux file systems like ext2/3?

Actually IOzone is a filesystem benchmark tool. The benchmark generates and measures a variety of file operations like sequential reading/writing, random reading/writing. So I want to customize my own ...
1
vote
1answer
112 views

How can I test the system footprint of applications?

I am about to develop a piece of software and I want to ascertain the impact it has on my system. The main things I am look for are load times, memory and CPU usage and shutdown time, although I would ...
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3answers
3k views

USB performance/traffic monitor?

First of all, I found a similar question but it doesn't really solve my problem. I am trying to discover if the USB bus for a device I am using is the bottleneck in my program. How can I monitor a ...
5
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5answers
467 views

performance monitoring

Is there some performace monitoring tool which would run in background gathering info about all system activity? Somethimes my system (Arch linux, 32 bit) slows down terribly and the top utility ...
37
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4answers
17k 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 ...
5
votes
3answers
1k views

Fast way to build a test file with every second listed in YYYY-mm-dd HH:MM:SS format

I want to create a large test file with lines containg dates listed by the second, but my method is taking inordinately long... (or at least, that's how it feels :) ... 43 minutes to create only ...