Questions tagged [performance]

The speed at which a program runs

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turbostat - TSC_MHz average MHz that the TSC ran during the entire interval

When using 'turbostat' command, we can see 'TSC_MHz' field data. What does 'TSC ran' here mean? OS in idle state?
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1answer
38 views

Disable Spectre and Meltdown mitigations

Can I disable Spectre and Meltdown mitigation features in Ubuntu 18.04LTS? I want to test how much more performance I gain when I disable these two features in Linux, and if the performance is big, ...
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1answer
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Profiling a Linux box to find causes of slowness

I use a (Fedora) Linux box for daily work, and generally I boot it every morning, so we are not talking about long running processes and short uptimes. Lately I noticed that the system got slow, but ...
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hugepagesz page table questions

trying to understand linux page tables... I am reading the RHEL 7 performance tuning guide and watching youtube vid of RH summit may 2018 https://www.youtube.com/watch?v=RLNMlsa173o* Having System H ...
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Image processing time shows periodic peaks

I have an ARM64 single-board computer with RK3399 CPU running Ubuntu 18. I wrote a Python script that acquires images from a USB camera and feeds them to a Caffe neural network. I measured the ...
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performance monitoring of “iptables” kernel module

I woul dlike to know, how much CPU / memory my current iptables rules consume. I tried looking in ps and htop, but even with kernel threads displayed, I don't see anything related to iptables. How ...
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RHEL CentOS 7 cpu performance tuning

On a shared memory 4 socket server having ~512GB DDR4 RAM or greater and greater than 64 cores running Intel xeon cpu's, taking any disk I/O out of the equation by doing systemctl enable tmp.mount and ...
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1answer
27 views

Measure startup times of tmux

I'd like to profile the performance of tmux. In particular how fast starting up a session is (and maybe also attaching to a session). I'm especially interested in how the content of my .tmux.conf file ...
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1answer
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Is a page fault across NUMA nodes “major” or “minor”?

I understand that on a single-socket Linux system, a command such as sudo ps -eo min_flt,maj_flt,cmd will generally count a page fault as "minor" if it blocks on a memory-to-memory copy, or on the ...
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Is there a way to artificially slow down Apache http server transactions to simulate load?

Is there a way to artificially slow down Apache http server transactions to simulate load? I'd need to force http transactions to take 100ms+ instead of the normal 3ms, without killing the CPU or ...
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14answers
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How can I speed up secure erasing of a disk?

I need to securely erase harddisks from time to time and have used a variety of tools to do this: cat /dev/zero > /dev/disk cat /dev/urandom > /dev/disk shred badblocks -w DBAN All of these ...
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How to protect my OS against any process consuming all resources?

I have a modern computer (7th gen i7, 16GB RAM, SDD) with up-to-date Ubuntu (18.04.2 LTS), yet I constantly run into the issue that certain processes completely freeze the computer. These are mostly ...
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5answers
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“Store” a remote SSH session?

I am trying to do these in a script. I have to run some commands on a remote host. Currently, I am doing this: ssh root@host 'bash -s' < command1 ssh root@host 'bash -s' < command2 ssh root@...
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1answer
96 views

Why does I/O cause my system to become almost nonresponsive, and how to fix it?

I'm recovering data from a hard disk. The disk is in good working order; a collection of files were deleted by accident. I'm using photorec, with the location to store recovered files on another ...
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3answers
60 views

grep a pattern across huge fileset without GNU parallel

I want to grep a pattern across 10M files really fast in a 36 core machine i tried this find . -name '*.xml' -type f | xargs -P 20 grep "username" >> output But i am getting some other ...
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Playing video is slow via XPRA

When using XPRA within a home-sized LAN, I find that the speed is a bit slow. Playing a video is like slowly playing a sequence of slides. How can I make XPRA faster or shall I use some other software?...
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1answer
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Multithreaded xz, with gzip, pv, and pipes - is this the most efficient I can get?

I'm excited to learn that xz now supports multithreading: xz --threads=0 But now I want to utilise this as much as possible. For example, to recompress gzips as xz: gzip -d -k -c myfile.gz | pv | ...
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1answer
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How to unbottleneck cpu-bound OpenSSH?

sneak@nostromo-2:~$ for i in 3des-cbc aes128-cbc aes128-ctr aes128-gcm@openssh.com aes192-cbc aes192-ctr aes256-cbc aes256-ctr aes256-gcm@openssh.com chacha20-poly1305@openssh.com; do openssl rand ...
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What's up with input on Linux 5.3?

I recently upgraded to Linux 5.3, and had a problem which significantly impacted usability: during some disk I/O spikes, mouse movements, and sometimes keystrokes, wouldn't register, so I couldn't do ...
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1answer
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Performance and security differences between Ubuntu and other linux distros [closed]

Assume I have a physical server with vanilla Ubuntu Server 18.04 LTS where I'll do some minimal configuration adjustments in iptables and /etc/ssh/sshd_config and only install docker. Using docker I'...
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cryptmount performance for large partitions?

Has anyone tried cryptmount with a large amount of data, say, several terabytes? Looks like a filesystem is stored in a single user disk file (such as ~/crypto.fs), so it makes me wonder if it can ...
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0answers
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Mount numerous SquashFS images

I am trying to configure a web server so that it can serve web apps using NGINX. We expect to have 15,000 different web apps. Each web app is supposed to be packaged in a SquashFS image, containing a ...
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Software RAID slows down while emptying buffer

I am experimenting with mdraid in CentOS 7.6, trying to understand these results from fio. I am doing a sequential write to a 4 stripe array, and the speed starts out good while it writes to the RAM ...
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What is 0.dylib.opt in linux

I'm running a multi-threaded server on a linux machine with 40 cores. The program has some serious bottlenecks since I cannot get the CPU utilization above 30% no matter how much load IO give it. The ...
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1answer
30 views

How to limit the amount of spillover to other CPUs from a single process

Please excuse the complete ignorance of my question - I'm probably lacking the right terminology here... I am trying to understand how a single process (R session) can spill over to all CPUs on our ...
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Server performance jitter after reboot

We are experiencing a strange linux server performance jitter problem: one of our app's P999 curves show that there exist severe jitter on some of our linux servers, while other linux servers don't ...
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1answer
46 views

How smart is the disk caching mechanism?

Linux's disk caching (page cache) is used to cache file data and uses as much RAM as possible. After upgrading my server's RAM I was able to download huge files faster than my disks would allow. But ...
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How to make Linux GUI faster?

Background (skip the following paragraph if you want to jump straight to the question): I'm a web developer, and have been using Windows since the beginning of my career. Over the years though, my ...
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RBP 3B+ horrible Kodi performance

I've tried a lot tips and tricks to get Kodi to work properly on my RBP 3b+ but so far, no luck. Maybe someone here recognises this issue and knows how to tackle it. setup: RBP 3B+ with the ...
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Why is this Linux process running so slow?

I've got a Python process on my Ubuntu 19.04 system that doesn't seem to be memory starved, yet is running a lot slower than I expect. The system has 96 GB of RAM plus 96 GB of swap. This process is ...
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1answer
46 views

Maximize RAID1 efficiency when using usb 2.0 and usb 3.0 interfaces

I have available a single USB 2.0 port and a single USB 3.0 port and would like to set up two HDDs (both USB 3.0) in RAID1. Not entirely sure how mirroring works, but was wondering if there was some ...
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Large file processing performance

I did a simple performance test of csv processing a while ago, and want to share results with community, maybe you can point out, what test could be more precise and fair. Firstly i took out 42 MB ...
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Debian bootchart2

I try to enable bootchart on debian to collect performance metric and build graphics. I follow this guid. The following approaches doesn't work for me: When system reboot press e and append command ...
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2answers
116 views

How can I make my sed script run faster?

I got this script my a related question of mine - How do I insert the filename and header to the beginning of a csv find . -name '*.csv' -printf "%f\n" | sed 's/.csv$//' | xargs -I{} sed -i '1s/^/...
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PC slows to a halt after I play more than 1 game of Rocket League

Here are my system specs. System: Host: mohammed-pc Kernel: 5.2.1-1-MANJARO x86_64 bits: 64 compiler: gcc v: 9.1.0 Desktop: i3 4.16.1 info: i3bar dm: LightDM 1.30.0 Distro: Manjaro ...
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Rebinding many keys at once

My goal is to have a very accessible way to remap many different keys. More specifically I want the number row and the home row to swap positions on my keyboard when I press shift+space. Right now I ...
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How we can get performance metrics from VTune in command line of Linux?

I am going to record all performance metrics mentioned https://software.intel.com/en-us/vtune-amplifier-help-cpu-metrics-reference by using VTune in command line for my C++ code. I used $ amplxe-cl -...
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2answers
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Why applications on FreeBSD run slower than on Linux?

Update They don't! At least, not for me. See my answer. Original question According to last year's Phoronix benchmarks, applications on FreeBSD mostly run slower than on Debian (including ...
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Can perf events detect deadlock in C++ codes (Linux)?

I am using perf tools to get some performance counters. I would like to know if it is possible to detect deadlock by checking performance counters included in perf events.
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1answer
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Why is Arch GPU performance faster than Debian and Windows?

I have used Linux for a while, recently switching to Arch, and decided to test frame rates in Arch, Debian, and Windows. I first installed Windows (just drivers and Firefox, for I wanted to remove ...
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dd measurement question

I am wrestling with some perceived performance issues on a 3-node HPE Apollo cluster running Linux. (The cluster supports a backup application.) These are very $$ servers. In our setup each node ...
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Want to capture host metrics for 60 min in every 3 sec through nmon

I want to run nmon for 60 min which will collect the host metrics in every 3sec. And to achieve this I run the below query on my host, nmon -ft -s 3 -c 60 /home/Documents/nmon When I analyze the ...
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1answer
37 views

How to speed-up programs launch with my ssd?

I have 2 disks on my machine: ssd and hdd. / mount point is on ssd, /home is on hdd. C:/ on my Windows 10 is on ssd, too. It seems to me that some programs (like Chromium web browser) launch much ...
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2answers
92 views

Alternative of too much slow gzip -d command

I'm using an production server for loading large data set to Hadoop to access from Hive table. We are loading subscribers web browsing data of Telecom Sector. We've large number of .csv.gz file (File ...
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3answers
127 views

System performance commands in Linux [closed]

How can I find determine real-time system performance parameters such as memory usage, CPU usage, disk usage from the terminal in Linux. I have asked Google but have not found a succinct suggestion. I ...
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0answers
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What is the relation between IO wait utilisation and load average

Load average uses processes that are running or runnable or in uninterrupted sleep state. So do the processes in uninterrupted sleep state correspond with the %wa as per the top command? Both are ...
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2answers
4k views

Why does my system use more RAM after an hour of usage?

I am using Arch Linux (5.1.8-arch1-1-ARCH) with the XFCE DE and XFWM4 WM. Things are pretty elegant and low on RAM and CPU usage. After the boot, and when the DE is loaded completely, I see 665 MiB ...
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1answer
1k views

How to diagnose slow upload speeds on Ubuntu Server 18.04

I'm currently running Ubuntu Server 18.04 on a home server build to act as a Plex server, among other things. I have it connected via ethernet (with a 5-port switch between it and the router), and get ...
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What are the performance overheads between logging in to another user account via ssh vs login

In Gnu/linux systems, I can perform a full local login (i.e. where logname returns the same output as whoami) by two methods: login: sudo login second_user (prompted for password) ssh: ssh ...
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1answer
108 views

Why does rename() take longer when fsync() is called first?

In this test, why does rename() take longer when fsync() is called first? Environment: btrfs, mechanical HDD, Debian 9 container, running on kernel 5.0.17-200.fc29.x86_64. Test command: dpkg -r ...