The speed at which a program runs

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5
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3answers
984 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
votes
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
votes
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
votes
1answer
583 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
vote
1answer
302 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
vote
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
votes
1answer
337 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
votes
2answers
617 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 ...
27
votes
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 ...
2
votes
2answers
857 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
votes
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
votes
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
283 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
621 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
votes
3answers
908 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
votes
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 ...
5
votes
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
votes
5answers
461 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 ...
34
votes
4answers
16k 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 ...
0
votes
3answers
278 views

Improving OpenOffice speed [closed]

I'm looking for some tips and tricks on how to improve the performance of OpenOffice on my desktop. Any ideas, tutorials or articles on this? Thanks in advance!
2
votes
1answer
625 views

what could cause large pagefault latencies in linux?

I'm running a Linux netbook with an SSD. Since the SSD is slow (and I don't want to wear it out) I've been running without swap. So far this has been great, but I recently put a new kernel on (2.6.37) ...
11
votes
1answer
2k views

How to make dpkg faster?

Package (un)installation on a Debian system is horribly slow, partly because it works with a whole bunch of (small) files. Short of getting faster storage, how do I speed it up? I'm thinking maybe ...
4
votes
1answer
575 views

“Split I/O”s on a Linux VM, disk alignment

I'm trying to figure out if there's some way I can tell if a system is being adversely affected by disk misalignment -- i.e. when I do a disk I/O operation, it actually needs to request extra blocks ...
25
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 ...
11
votes
4answers
9k views

Use of O_DIRECT on Linux

If this question is too programmer oriented, let me know. I wonder if there are people familiar with the O_DIRECT flag for the open() system call on Linux 2.6? Linus disparages its use, however high ...
2
votes
1answer
438 views

xorg performance in openoffice

I've just been monitoring my cpu usage in openoffice calc when cells have been copied vs when they haven't and seen a dramatic increase in cpu usage for the Xorg process. The additional rendering ...
16
votes
2answers
6k views

Why does high disk I/O reduce system responsiveness/performance?

I never quite understood why high disk I/O slowed the system so much. It's strange to me because I would expect the slow-down to affect only those processes dependent on the hard/optical drive data, ...
9
votes
1answer
1k views

What's the progress regarding improving system performance/responsiveness during high disk I/O?

Whenever there is high disk I/O, the system tends to be much slower and less responsive than usual. What's the progress on Linux kernel regarding this? Is this problem actively being worked on?
11
votes
1answer
6k views

How can I configure cgroups to fairly share resources between users?

There used to be a kernel config option called sched_user or similar under cgroups. This allowed (to my knowledge) all users to fairly share system resources. In 2.6.35 it is not available. Is there a ...
6
votes
3answers
929 views

zsync vs. jigdo

What's the difference between zsync and jigdo? Their core functionality seems the same, so I'm curious on things like performance, file size, and ease-of-use. Would also be interesting to know why one ...
7
votes
6answers
4k views

Sync writes very slow. Ubuntu 10.10, 32 bits, ext4

I am running ActiveMQ on my Macbook Pro that runs Ubuntu 10.10, 32 bits with an ext4 partition. Linux iker-laptop 2.6.35-23-generic-pae #40-Ubuntu SMP Wed Nov 17 22:32:51 UTC 2010 i686 GNU/Linux If ...
6
votes
2answers
884 views

I/O-overhead of dm-encrypted device?

What would be the Read-/Write-overhead when using dm-crypt (LUKS) as full disk-encryption (including root partition) on a Linux-Desktop (Ubuntu)? I plan to stack it like so: LUKS > LVM > ext4 The CPU ...
17
votes
5answers
9k 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 ...
87
votes
7answers
29k 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, ...
2
votes
4answers
7k views

What is “System Memory ” displayed in nmon in AIX?

I have a host with AIX 6.1 (6100-04-02-1007) upgraded from AIX 5.1 with Veritas Storage Foundation 5.1. Since the upgrade from AIX 5.3 to 6.1, Run vx services means a lots of memory consumed that I ...
6
votes
4answers
213 views

Quantify unix responsiveness

I am one of the n users of a shared unix machine. For reasons unknown, the machine is not "responsive" enough. For example, it is slow on interactive commands, it takes few noticeable moments for any ...
7
votes
2answers
9k views

Diffing two big text files

I have two big files (6GB each). They are unsorted, with linefeeds (\n) as separators. How can I diff them? It should take under 24h.
15
votes
3answers
8k views

How do I minimize disk space usage

One of my machines is the 2GB EeePC Surf, a neat netbook with very limited resources. So limited that right now, I have 22MB free space left. On it, I'm running Arch Linux with the Openbox DE and a ...
3
votes
2answers
812 views

Does the Linux PreemptRT patch benefit desktop users?

Does the PREEMPT_RT patch (real-time kernel) have any benefit for regular desktop users?
19
votes
3answers
4k views

Measure pipe throughput in the shell

There is a shell command that allows to measure how fast the data goes through it, so you can measure the speed of output of commands in a pipe. So instead of: $ somecommand | anothercommand you ...
21
votes
11answers
9k views

the lightest way to have a GUI in Linux? [closed]

I have been using Gnome and KDE for a while, and I am now running Compiz standalone... Regarding system resource, I think the most heavy ones are feature-rich desktop environments (Gnome, KDE), then ...