Questions tagged [performance]

The speed at which a program runs

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7 views

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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3answers
437 views

Performance of calling POSIX-specified functions versus direct Linux kernel calls

In an answer over on Stack Overflow, I provided a code sample to perform some small task referenced in the question. The original question had to do with the fastest-performing technique (so ...
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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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1answer
7k views

How to ensure exclusive CPU availability for a running process?

At first, the question seems to be a little bit silly/confusing as the OS does the job of managing process execution. However, I want to measure how much some processes are CPU/IO-bound and I feel ...
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1answer
258 views

Is “top” accounting for Kernel Interrupts?

I have a simple interrupt that is triggered by a GPIO-input. The IRQ only increments a variable and returns. When I turn the frequency of the interrupts up to somewhere around 10-20 kHz, the system ...
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1answer
49 views

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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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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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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27 views

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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2answers
68 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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1answer
31 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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101 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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1answer
63 views

Can I distinguish between swap thrashing and non-swap high IO latency somehow?

My system becomes much, much less responsive, every time I clone a VM image. I'm using virt-manager, and I can see the IO is performed by several qemu-img convert threads. I tried to gather some ...
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2answers
3k 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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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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3answers
326 views

Display “burps” every 30 seconds

I'm running Mint 18 on a Dell i7 and I have this annoying issue that I can't find where its coming from. Every 30 seconds the display freezes for about 0.5 seconds. The issue is persistent and ...
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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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1answer
1k views

Why is my UDP bandwidth significantly lower than TCP bandwidth in iperf

I am running a simple bandwidth test between two VMs using iperf. I am getting very different bandwidth reading for TCP and UDP where the UDP bandwidth is terribly lower than TCP. TCP: root@i-sahmed-...
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1answer
62 views

Could AIO fsync improve dpkg performance?

Could dpkg, the Debian package manager, gain a noticeable performance improvement by using one of the AIO fsync() operations, instead of sync_file_range() + fsync()? The [proposed] fsync2() API is ...
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1answer
59 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 ...
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2answers
1k views

Fedora 25 Running Slow After Software Update

I've been running Fedora 25 on my machine for a couple weeks now. I happened to shut down the machine, and there were some software updates that automatically installed. After booting the next time ...
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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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Slow wired connection on Linux but normal speed on Windows

I installed Ubuntu, Pop_OS, Manjaro, Neon, and Deepin, to my desktop PC (specs at bottom). My internet speed was very slow, basically unusable. Windows gives a normal 15 Mb down and 10 Mb up, but ...
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1answer
76 views

How to limit frame-rate for all games on Linux?

System Linux Mint 19.1 Cinnamon 64-bit, based on Ubuntu 18.04 LTS. Related Hardware CPU: Intel Core i7-7700HQ (Ark Intel) GPU: NVIDIA GeForce GTX 1060 6GB (Max-Q Design) Screen: 4K laptop 15.6 inch ...
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1answer
29 views

Slow IO on OracleVM [closed]

We have a slow disk speed problem on the oracle vm's. Actually we have a same config two diffrent OVM(rac1, rac2), they works like active passive.they are oracle DB servers. One of them(rac1) no disk ...
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2answers
113 views

NVMe disk shows 80% io utilization, partitions show 0% io utilization

I have a CentOS 7 server (kernel 3.10.0-957.12.1.el7.x86_64) with 2 NVMe disks with the following setup: # lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT nvme0n1 259:0 0 477G 0 ...
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Huge hdd usage while gaming

For testing I tried to run Path of Exile and Guild Wars 2 on Ubuntu Budgie and Mint XFCE. To run PoE I used steam. To run GW2 I used Lutris. When any game is fully loaded and I do not touch anithing ...
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1answer
28 views

Does the “watch” command put stress on a scheduler?

I have an account on a compute cluster which uses the SLURM scheduler. I have some jobs in the queue and I'm using the "watch" command to see their status: watch squeue -u myUserName Does constantly ...
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2answers
2k views

Write access time slow on RAID1

I'm running MongoDB on my personal computer. I noticed that performance is much slower when the data are on my 2-recent-spinning-hard-drive-software-RAID1 than when they are on an older spinning hard ...
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1answer
31 views

Performance reduction activating trace-functionality in kernel

Is there any performance reduction to be expected from just activating trace (ftrace) functionality in the Linux kernel, but not using it at run time?
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1answer
134 views

transmission-daemon: UDP Failed to set receive / send buffer

I just compiled the transmission{-daemon,-cli} on my Debian 10 Buster, and installed it with some minor and major problems. One of those minor ones is apparent failure to set UDP receive buffer / ...
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1answer
749 views

btrfs balance taking way too long

I have a btrfs RAID1 array (two 891GiB partitions on two HDDs) on my laptop. When I run btrfs balance it takes a huge amount of time to complete. I know if I would like to balance the whole ...
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1answer
135 views

Case insensitve tab completion zsh without increasing startup time significantly

So I wanted to get away from oh-my-zsh because it made my shell startup lag noticeably (>0.1s). Indeed, after removing oh-my-zsh the startup time went to 0.02s but now I started adding features ...
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1answer
80 views

Improve performance when using “system” call (shell escape) processing large files in awk

I have an awk script that processes very large files that look something like this: K1353 SF3987.7PD833391.4 KARE K1353 SF3987.2KD832231.4 MEAKE K1332 IF4987.7RP832231.2 LEAOS K1329 SF2787.7KD362619....
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2answers
2k views

Huge page and performance improvemnt

How can using huge page improve performance? I have read that huge pages improve performance by reducing TLB lookups and reducing the size of the page table. Can someone tell me how this helps with ...
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3answers
3k views

CPU > 80% - how can I debug?

I am running a laravel application on a Ubuntu 14.04 digital ocean vps and I am using New Relic to monitor the server. I got an email alert that my CPU usage was above 80%. I logged in to New Relic ...
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0answers
9 views

In MPM “event” mode, when force killing an Apache2 process, what is the mechanism that creates a set of new Apache2 processes?

In MPM "event" mode, when force killing an Apache2 process, all other spawned Apache2 processes are killed. Within seconds, a batch of new spawned Apache2 processes are started by the main Apache2 ...
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1answer
76 views

IO wait time is higher than disk utilization. Isn't this impossible? [duplicate]

I am trying to improve my understanding, following this (so far) unanswered question: Possible limiting factor during upgrade of Fedora VM - not disk or cpu or network? I ran the following test load, ...
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1answer
38 views

Implications of using a plain string command instead of a function in .bashrc (particularly for PROMPT_COMMAND and PS1)

I have trouble understanding: How is .bashrc parsed How are bash functions constructed I try to customize my terminal prompt. My .bashrc make use of PROMPT_COMMAND like this (it's actually much more ...
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4answers
32k views

grep: memory exhausted

I was doing a very simple search: grep -R Milledgeville ~/Documents And after some time this error appeared: grep: memory exhausted How can I avoid this? I have 10GB of RAM on my system and few ...
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0answers
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Possible limiting factor during upgrade of Fedora VM - not disk or cpu or network? [duplicate]

I'm upgrading a VM from Fedora 29 to Fedora 30. I triggered the update from inside GNOME Software. It downloaded the upgrade, and asked to reboot. It started installing... atop shows the qemu ...
2
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1answer
37 views

Finding performance bottlenecks on Red Hat server hosting KVMs with QEMU?

As a side task I administer a RHEL 7 server used as an internal KVM host. Now it runs eight VMs which, but for one, are idle most of their time, or at least not doing anything at all resource ...
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4answers
3k views

any large inode size benefits? (ext4)

From some foggy memories I thought I would "improve" the default settings when creating a Linux partition and increased the inode size to 1024, and also turned on -O bigalloc ("This ext4 feature ...
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11answers
6k views

Why doesn't shell automatically fix “useless use of cat”? [closed]

Many people use oneliners and scripts containing code along the lines cat "$MYFILE" | command1 | command2 > "$OUTPUT" The first cat is often called "useless use of cat" because technically it ...
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3answers
18k views

ulimit & rlimit in Linux, are they the same thing?

I see people use the terms ulimit & rlimit interchangeably, can I say they are referring to the same thing?
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1answer
280 views

Huge performance difference of the command find with and without using %M option to show permissions

On my CentOS 7.6, I have created a folder (called many_files) with 3,000,000 files, by running: for i in {1..3000000}; do echo $i>$i; done; I am using the command find to write the information ...
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0answers
40 views

Small delay in sudo

I want my zsh prompt to display whether the session has sudo rights (from a previously run sudo command). After looking at the answers to this question, I arranged to use the exit status of sudo -n ...
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3answers
978 views

Why does find -inum iterate through the whole filesystem tree?

It surprises me to see find iterate/walk through the complete filesystem when I do a simple find -inum 12345 Without background info it seems to me that there should be much easier ways for to tell ...
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1answer
5k views

RHEL 7 Still CPU Frequency Scaling

When machine is imaged with: RHEL6.x CPU speeds report full 3.3Ghz speed for all CPUs cpupowerutils is not installed RHEL7.x CPU speeds vary (shown in example below) cpupowerutils is installed I ...