The speed at which a program runs

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4
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1answer
76 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 ...
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 ...
3
votes
1answer
98 views

Artificially prime buffer cache?

Is it beneficial to artificially prime the buffer cache when dealing with larger files? Here's a scenario: A large file needs to be processed, line by line. Conceptually, it is easy to parallelize ...
1
vote
1answer
94 views

apache mod_security and performance

I have a list of bots to block, so I was thinking that fail2ban could be a solution until I realized that mod_security would be more efficient in this kind of tasks. The number of bots is huge, so ...
0
votes
1answer
27 views

Understanding high load average with vmstat, mpstat, sar, and top

I am trying to understand the load average on my system when idle. Here are some results after the system has been running for a few hours, with almost nothing installed. vmstat root@arm:~# vmstat ...
0
votes
1answer
49 views

Where is NMon cron job for AIX?

While trying to know where is NMon job configured to run; I do find that it's NOT listed on Crontab (using crontab -l). BUT - the job is currently running as expected, which is weird. See the ...
0
votes
1answer
78 views

Powerful Workstation

I heard about ILM's (Industrial Light and Magic) workstations on which they create models and scenes for a lot of different movies. They have workstations with more than 1024 GB of ram and a lot of ...
4
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0answers
31 views

What is the IPsec bottleneck in Linux?

I am trying to compare the performance of several network security protocols between two hosts connected in Gigabit Ethernet. My goal here is to see if I can saturate my bandwidth, and if not, what ...
4
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0answers
53 views

Fixing terrible performance when watching/reading video and writing video files to disk

I have had this issue for quite some time and tried many times to fix it on my own and it always fails. IP schedulers, ionice and things like that always yield no result. I even went and bought an ...
4
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0answers
488 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). ...
2
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0answers
13 views

JVM low-memory tuning

What command-line options would provide the lowest memory-footprint JVM, in OpenJDK, or possibly other JVMs (Linux/Debian)? I'm willing to disable JIT, live with slow or choppy garbage collection, ...
2
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0answers
30 views

Why does my fresh Debian have a high latency?

The time between clicking and seeing a response is very high. Typing looks very funny, and makes me feel queasy. I think there's about 50-20ms "extra". I would expect a top notch linux distro to have ...
2
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0answers
23 views

Many transient files on journaled filesystem?

Writing and deleting many files quickly I'm going to write many temporary files per second, over a sustained period. Each will be deleted after some milliseconds. Say we have an image processing ...
2
votes
0answers
69 views

Cgroups - memory subsystem

I want to set the memory.limit_in_bytes parameter for a control group and disable OOM, so processes freeze when the limit is reached. But i want to change that limit dynamically, if there is more ...
2
votes
0answers
412 views

Local disc copy at 10MB/s! What could be the problem?

I am running a Debian 6.0.6 (before you ask). I have a regular desktop computer, nothing fancy... but when I copy a file using nautilus I am getting 10MB/s copy speed and the system is completely ...
2
votes
0answers
768 views

Send print job to printer immediately without queueing, aka increase print performance

I have a ruby/rails web application, one action of which sends PDF files that have been generated by the app to a Xerox 4127 printer on the network. This is accomplished via shelling out and running ...
2
votes
0answers
483 views

Why if I don't disable nm-applet and xfce4-volumed my startup slows down?

I'm running Xubuntu 12.04, and after I ran the update, my login started slowing down big time. I've dabbled a little bit with the programs in Settings -> Settings Manager -> Session and Startup, and ...
2
votes
0answers
578 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 ...
2
votes
0answers
240 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
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0answers
257 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
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0answers
348 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
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0answers
70 views

'nc' using ~100% CPU when transferring a FIFO file

On the server which is always connected I’m using this in a crontab: @reboot nc -k -l 1337 < /tmp/fifo.fifo On the client which is not always on the network or switched on I’m using this ...
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0answers
48 views

Variations in Ubuntu 12.04 /usr/bin/time statistics

I have a command line tool which I run on Ubuntu 12.04.5 LTS. I need to calculate the cpu time for this program. I have been checking /usr/bin/time function. command: /usr/bin/time -v -a -o ...
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0answers
52 views

How to diagnose CPU performance problems?

Recently I bought a new netbook based on AMD A4-1200 CPU and installed Linux Mint 17 with XFCE. RAM is 4GB So, testing some of my programs, I found very strange behavior. On random intervals, the ...
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0answers
48 views

Properly mount a windows share to move files on the mountpoint

This question resulted from a question of mine on stackexchange. I mount a windows share with mount -t cifs -o ...
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0answers
28 views

What tools can show me the CPU usage that doesn't appear in top/sar?

I have a virtual machine that's using ip_tables to set up some connection forwarding. According to top, sar and /proc/stat, I'm > 99% idle. However, perf says I'm only about 72% idle, with the rest ...
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0answers
247 views

Horrible Iceweasel and Opera performance when watching youtube

I have 64-bit Debian on laptop with Intel Core 2 Duo T9300 2.5GHz, Nvidia Quadro NVS140M GPU and 4GB RAM. For now - im on vacation and im using 3G USB modem. I have relatively slow but high quality ...
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0answers
46 views

Ubuntu with LAMP+Mediawiki suffering spikes

I'm sorry if this question is off topic, but I'll give it a shot: I have a VPS running Ubuntu 12.04, a LAMP stack, and Mediawiki. After installing Mediawiki I noticed that my wiki site was spiking, ...
1
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0answers
88 views

Do kernel threads seem to interfere with full tickless mode?

I'm trying to disable local timer interrupts for low latency. I have full tickless mode enabled in the kernel config and I have the boot parameter nohz_full set for the cores in question. However ...
1
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0answers
153 views

Monitoring Disk Latency

We have quite a few physical machines in our environment, yet we have no trending data over a period of time for disk latency statistics. We can easily run the standard iostat commands to see what the ...
1
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0answers
20 views

Amount of memory transfer on a running Linux

Can I determinate the amount of RAM exchange (between the CPU and the RAM) on a running Linux system? I'm not looking for the max RAM speed (then memtest would be valid answer). I'm looking for the ...
1
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0answers
43 views

memory consumption alert

My VPS has reported a memory consumption alert says reached 273% and I cannot access any of my sites. But I checked on the terminal today and it does not look like a memory problem. Am I correct in ...
1
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0answers
180 views

Why does my CMS run extremely slow in my workstation (Ubuntu)

For over a year I have been struggling with the response speed on my Drupal v7.2x CMS install. Let me explain. I'm running Drupal 7.2x on an Ubuntu 12.10 (upgrade to 13.xx pending) for the purpose of ...
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0answers
248 views

X high CPU when using Java applications

Only recently, my Freemind program has become extremely sluggish and unresponsive (big lag) when moving my mind map around. I use Arch Linux with xfce4. Freemind is made with Java. If I move the mind ...
0
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0answers
63 views

SEGFAULT error 4 in libX11 on another X display caused by War Thunder

I read tons of info about performance boosting for linux gaming. One of them is to run games on a separate X server. After hours of search and tries, I ended up with something "working" for most of ...
0
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0answers
46 views

AIX CPU usage - how to know how many CPUs running?

Over AIX 6.1 - I do see the following output, it says I have 16 Max Physical CPUs; but there are only 8 active - why is that? The system will use the remaining 8 if needed? Or are they disabled? # ...
0
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0answers
17 views

Using `perf` repeatedly with file input

perf can be used to analyze the performance of a program. Say you want to test the performance of a program prgrm, with input from a file, you can run: perf stat prgrm < inp.dat Now when you ...
0
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0answers
22 views

run netperf without IP address available

I have DPDK set up, with two NICs taken over by DPDK, i.e. the interfaces are not visible to userspace applications. Now, I need to run netperf/iperf to measure throughput performance of port-to-port ...
0
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0answers
25 views

netperf: run with no control connection

Trying to run netperf without setting up a control connection between netperf and netserver: client% netperf -N -H 10.0.0.2 ... netperf: send_omni: connect_data_socket failed: No route to ...
0
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0answers
123 views

Virtualized Debian Jessie: slow booting / shutting down :(

I have a Debian 8 (Jessie), cat /proc/version says: Linux version 3.16.0-4-amd64 (debian-kernel@lists.debian.org) (gcc version 4.8.3 (Debian 4.8.3-16) ) #1 SMP Debian 3.16.7-ckt2-1 (2014-12-08) ...
0
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0answers
166 views

Increasing ulimit stack size benefits?

Hello I'm new in Linux and at my work I have a server that runs a banking software. The company that made the software said that the stack size should be set to unlimited. Does this make the software ...
0
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0answers
37 views

Xorg consumes CPU, RHEL 7 fresh install

I've installed RHEL 7 with default settings. I wonder why Xorg consumes 30% of my CPUs. How can I know what's wrong and how to fix it? HP DL360p Gen8, dual Xeon E5-2640
0
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0answers
28 views

Pentium D and GeForce 6700 does not have enough power to play DVD full screen

I have an older computer which I would like to use as a DVD and video file player. These are the specs: CPU = Intel Pentrium D @ 3 GHz RAM = 1 GB GPU = NVIDIA GeForce 6700 XL HDD = 229 GB OS = Ubuntu ...
0
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0answers
28 views

How can we measure performance overhead resulting from writing to files or folders?

I have a tool which takes as input a folder or a file and then it logs operations done on that file or folder (modifying,deletion,creating new folders or files, etc). I was looking for a way to ...
0
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0answers
89 views

Why would attempts to bind affinities for rcu kthreads fail?

I am trying to get full tickless mode working on my box on Ubuntu kernel 3.10.39. I am running the following command: for i in `pgrep rcu` ; do taskset -pc 0 $i ; done It seems to work on some of ...
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0answers
163 views

Ubuntu 13.10 x64 - slow and acting strangely gvfs+NTFS

I have updated Ubuntu 13.10 x64 to latest stable releases of all packages. I'm running GNOME and using SSD disks on USB 3.0 ports in lenovo Y500 notebook. I'm using Midnight Commander (as root) in ...
0
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0answers
40 views

Can ramdisk improve performance when stats show low wait and system cpu use?

I have jobs that do I/O of rates peaking around 200mb/s. On high load (over twice cpu cores) I tried to copy large file and got only few mb/s. Gathered dstat show single digits in wai and sys category ...
0
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0answers
62 views

OTG musb and full speed bulk endpoint throughput

We are developing an application on an OMAP3 device (DM3730 ti). An acquisition board gets samples and sends them to the OMAP board via USB. This acquisition board does a 16KHz sampling which ...
0
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0answers
33 views

If a buggy application underperforms, it it possible server tuning could have no affect?

To set the stage, imagine if you will: A read-heavy Tomcat Application with MySQL on Red Hat Enterprise Linux with some problematic Java Class files which resulted in the application performing a ...
0
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0answers
266 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 ...