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2
votes
0answers
305 views

Software raid checksumming slow

On my new 24 disk array I get 900 MB/s of raw read or write using dd to all the disks. When I set the disks up as a 24 disk RAID6 I get 400 MB/s write and 600 MB/s read. It seems to be due to ...
1
vote
2answers
1k views

Opensuse 11.4 very slow on 8 GB RAM i5 processor

EDIT : This is when top is run with "M" . Snapshot when Eclipse starts ( using "iotop") Snapshot when Eclipse building workspace After Eclipse has done its thing Its as slow as before ...
2
votes
2answers
15k views

High load average, low CPU usage - why?

We're seeing huge performance problems on a web application and we're trying to find the bottleneck. I am not a sysadmin so there is some stuff I don't quite get. Some basic investigation shows the ...
2
votes
2answers
1k views

vmstat IO stats: why the high bo during a download?

On my RHEL 4 machine, I was downloading a huge file (2.5GB)..I was checking the output of vmstat and was especially curious about seeing the disk IO using bi and bo. I know iostat is a better tool ...
2
votes
3answers
3k views

Faster awk script to get the substring / string we wanted

ORDER EVENT .........[] [] ... so many other tags... [Account<25106>=ACCT1] [Destination...] .. so many other tags. I am currently trying to get the account like this. I tried using match in ...
1
vote
2answers
628 views

using SSH to connect to remote CentOS 5.6 server where Firefox running on server is very slow [duplicate]

Possible Duplicate: How to speed up X over SSH on a slow network connection? I've installed firefox on CentOS 5.6 and I'm using X11 SSH to remotely login to view the browser. Firefox ...
4
votes
1answer
74 views

Timescales of any task in linux kernel?

I am studying how Linux kernel works and getting interested in the timescale of anything that happens in the kernel. Of course I know it depends on the HW, but would like to get an example. For ...
1
vote
1answer
114 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 ...
3
votes
1answer
2k 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
156 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 ...
43
votes
5answers
23k 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 ...
5
votes
1answer
855 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 ...
6
votes
3answers
6k 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 ...
7
votes
3answers
754 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 ...
4
votes
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
votes
3answers
15k 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
86 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
votes
2answers
768 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
votes
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?
2
votes
0answers
462 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). ...
9
votes
4answers
10k 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 ...
10
votes
1answer
5k 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
votes
5answers
2k 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 ...
21
votes
4answers
13k 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
vote
1answer
136 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 ...
5
votes
3answers
819 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 ...
1
vote
1answer
273 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 ...
0
votes
1answer
142 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?
2
votes
1answer
318 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
599 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 ...
25
votes
3answers
1k 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
631 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 : ...
3
votes
1answer
1k 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 ...
1
vote
2answers
3k 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 ...
22
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 ...
3
votes
1answer
926 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
278 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 - ...
5
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 ...
3
votes
3answers
562 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, ...
25
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
826 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 ...
4
votes
2answers
2k 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
1k 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
104 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 ...
4
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 ...