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6
votes
3answers
573 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 ...
15
votes
3answers
11k 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
81 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
636 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
1k 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
430 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). ...
8
votes
4answers
8k 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 ...
7
votes
1answer
4k 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
996 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 ...
19
votes
4answers
11k 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
128 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
591 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
1k 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
250 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
133 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
296 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
583 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 ...
21
votes
2answers
715 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
481 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
2k 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
3answers
1k 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
769 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
268 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
2k 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
523 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, ...
24
votes
1answer
1k 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 ...
3
votes
3answers
757 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 ...
2
votes
0answers
944 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
989 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
101 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
2k 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 ...
4
votes
5answers
375 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 ...
24
votes
4answers
7k 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 ...
-1
votes
3answers
260 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!
1
vote
1answer
443 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) ...
7
votes
1answer
1k 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 a faster storage, how do I speed it up? I'm thinking maybe ...
4
votes
1answer
521 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 ...
20
votes
6answers
5k 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 ...
10
votes
4answers
6k 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
397 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 ...
13
votes
2answers
4k 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?
9
votes
1answer
5k 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 ...