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8
votes
2answers
968 views

What keeps one side of an rsync so busy?

I've got a Debian machine on my LAN serving as a backup server for the others. It has four HDDs combined into a software RAID 5 md device, on that an LVM, and on that btrfs. Backups are made using ...
7
votes
1answer
2k views

Why is ping so slow?

My setup: Server in the cellar + GBit switch. Long cable to the roof. GBit switch. I have three computers in the roof. One has only 100MBit ethernet, one laptop with GBit and a new computer. Ping ...
6
votes
2answers
697 views

Does the position of partition on disk affect speed?

If I put /var as first partition, then /home and /, will the partition for /var have better performance than if I put other partitions close to head of the disk? Will the disk sector position matter? ...
2
votes
1answer
172 views

How to find what's hogging what resources? [closed]

I've found lots of similar questions, but nothing that's exactly right. I'm trying to figure out what's making one server run slower than another. I'm hoping for something that would say something ...
4
votes
2answers
2k views

Linux running slow with 0 swap left

Our Linux server is responding very slowly. top doesn't show any excessive CPU usage. I noticed that even though there's about 5GB of free memory, the system is using all of swap with no free swap ...
0
votes
0answers
252 views

write file to NFS speed issue

I have a big data file need to write to NFS directory which is mapped under a Windows system. I had 2 different approaches to achieve this. I wrote (using the “save as” command) from the app directly ...
5
votes
4answers
2k views

How to get better desktop performance in linux?

Normally I do not care much about desktop - performance, since my servers do not run any gui. But at home I run some older hardware (Pentium) which gets sometimes very sluggish (mouse-movements in ...
4
votes
2answers
1k views

Is it possible to trigger OOM-killer on forced swapping?

Is it possible to have the system preemptively swap out inactive pages (vm.swappiness), but invoke the oom-killer when the system runs out of RAM (as opposed to running out of memory) and is forced to ...
3
votes
2answers
1k views

NFS Option Reload without Service Restart

What do I need to do to change the RPCNFSDCOUNT setting without a full service restart? I need to reload the NFS configuration without restarting the service. The RPCNFSDCOUNT thread count is too low ...
3
votes
1answer
507 views

How do I tell if a Wine application uses hardware or software rendering?

I'm building an appliance/kiosk-type machine which is going to run a single fullscreen Wine application (Synthesia). I'm using Arch Linux running LXDE on an original 7-inch EeePC (well, souped up to ...
13
votes
1answer
2k views

Is disabling barriers for ext4 safe on a laptop with battery?

The manual page says about the barrier option for ext4: Write barriers enforce proper on-disk ordering of journal commits, making volatile disk write caches safe to use, at some performance ...
2
votes
0answers
537 views

“Remote function call interrupts” (CAL in /proc interrupts). What is it?

I'm running a test program which generates a large number of threads and asynchronous I/O. I'm seeing very high counts of these interrupts in /proc/interrupts, the program cannot scale beyond a ...
6
votes
1answer
6k views

How to configure a filesystem+LVM for effective usage of SSD?

ext4 is one of the filesystems recommended for using on SSDs (with a number of built-in techniques and advices how to tune it for better performance and wear-levelling of SSDs). I want to install a ...
7
votes
1answer
2k views

Throttling web crawlers

My website is being DoS'ed by Google webspiders. Google is welcome to index my site, but sometimes it is querying a tagcloud on my site faster than my webserver can produce the results, making my ...
0
votes
2answers
426 views

Optimize command yum

I would like knowing if there is a way to increase the performance of the command yum to install and search packages. I'm a very happy new user of Fedora 16.
2
votes
0answers
231 views

Connected external HDD slows down system

I need to connect large external hard disks (with many many files) to a system running Ubuntu. I have no idea how the Linux kernel is treating the inodes for the external drives, but attaching huge ...
2
votes
0answers
239 views

Perform test of aes-ni and aes module in linux kernel

Since both aes-ni and aes module are available in linux kernel , how can I give it a performance test , to decide which one's faster ?
2
votes
1answer
281 views

How do I record disk performance on slow hardware and then replay it to faster hardware and benchmark it?

I am currently performing various development tasks that are slow on my current system because of IO performance. Is there a way to record disk operations while performing IO consuming tasks, ...
4
votes
1answer
3k views

What's faster, dd 1.5TB or rsync 500GB?

I need to save data from a failing hard drive. Sounds like ddrescue or myrescue (or maybe clonezilla?) will be my best friends here, but I'm just wondering what will likely be faster: using ...
2
votes
0answers
317 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 ...
3
votes
2answers
17k 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
2k 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
4k 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
648 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
75 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
3k 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
163 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 ...
47
votes
5answers
25k 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
866 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
821 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
17k 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
811 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?
3
votes
0answers
472 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
11k 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
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
14k 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
138 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
867 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
280 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
145 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?