Questions tagged [performance]

The speed at which a program runs

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Why does the Linux kernel not use rust?

I have heard that the Linux Kernel uses rust. I don't know much about the programming language except that it has the potential to run faster than C. According to websites Rust is more safe than C ...
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Ubuntu18.04 - scaling_cur_freq is lower than scaling_min_freq

While using the server, we have confirmed that the clock speed is very low only for a specific CPU group. Could you please tell me the cause and solution for this? All cpu's cpuinfo_min_freq and ...
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How to determine cause of poor CPU performance - AMD 75F3?

I have 2 identical machines with pretty identical configurations, however one machine is performing much worse than the other. After some digging it appears the CPUs on one machine is simply slower ...
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Why 7z not using enough CPU?

CentOS 9. 3 vCPU VM with 4Gb RAM. I run a cron job with 7z compressing 35Gb data in 150 files 7za a -mx=9 -mmt=3 ... RAM usage - 18%, disk queue is very small, CPU is 61% on average. Why not 100% ? ...
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Understanding of BPF

When I need to capture some packets using tcpdump, I use command like: tcpdump -i eth0 "dst host 192.168.1.0" I always think the dst host 192.168.1.0 part is something called BPF, Berkeley ...
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High latency of network related operations

I have a server running Debian 11 with two 1Gbps and 10Gbps uplinks respectively. When running any network related commands, I observe a very high latency at the beginning of the command execution. ...
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how does btrfs' copy-on-write feature influence with database application(such as postgresSQL)?

I'm working on manjaro KDE whoes whoal / partition (excepting /boot/efi partition, of course) has formated to btrfs filesystem, and its copy-on-write feature remains default. Just now, I was following ...
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HDD write speed on gpt vs lvm, baremetal vs kvm

I'm comparing write speed of HDD storage from two sources - baremetal, kvm and on two formats - gpt partition, lvm partition. Commands have been run thrice and I checked the average value. I used one ...
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What do results of Linux time wrapper tell me happened to this cp command?

My view on this issue is from the developer side. I write the code that gets placed on a RHEL virtual machine running as one of many in an enterprise system. The filesystem being used is a remote, ...
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Speeding up boot process on a Debian server

I run a Xeon server from Dell with SATA Samsung SSD 860 PRO. I am looking for a way to speed up its boot time. Is there a way for me to speed up boot time (ssh reachable time to be exact)? I can see a ...
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Running computations from SWAP without complete performance drop - Discussion on NVMe speeds and if they ever come in reach for RAM replacements

I have been setting up my Linux machine (currently pop-os) in several ways recently to upgrade my system to demands of specific data analysis done in R. In brief: The Data set I am working on is ...
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loop-device performance issue

I am trying to work with dm-mapper and it doesnt accept files. so i need a device. So i have created a 1500M file on ram(ramfs filesystem) at /dev/shm/f and mapped it to /dev/loop0(by losetup). But i ...
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Speeding up `badblocks` by tweaking its `-c` switch

I have just tried upon tweaking the badblocks utility to use more RAM and possibly achieve a bit higher performance. The exact command I am running is (without HDD's S/N): badblocks -v -b 4096 -c ...
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Why are consecutive find commands faster? [duplicate]

I noticed that when using find <dir> -depth for the first time on a directory, it consumes quite a lot of time, but the next times even when searching for a different pattern, it seems pretty ...
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New computer running arch linux gets weirdly loud

I have a relatively new computer and I just installed Arch linux. From the moment I start the computer, it starts with a loud noise that is very similiar to a computer running on 100% of the CPU. From ...
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Why is `rpm -qa base*` so terribly slow?

I wonder: rpm uses a (simple) database to store things like packet names. When using rpm -qa to query that database, it is terribly slow. For example, this command took almost a minute to complete ...
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md RAID5 array performance loss with drive swap

I have had, for a very long time, an md RAID5 array in a little server I keep at home for general storage. The current incarnation has two SSDs in RAID1 for boot/root purposes and 10 drives on two ...
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Why does redirecting lines ≥1022 characters take 83× longer than redirecting lines ≥1021 characters?

I have a text file of around 10 MB containing around 50k lines. When I select all lines ≥1021 bytes and redirect the output to a regular file or pipe it to cat, it takes 0.135s. When I change this ...
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Do linux serivce accounts have limited resources by default?

distro: Ubuntu 20.04 Desktop Arm64 board: Raspberry Pi 3 I'm running a flutter embedded application that is displayed via gbm/drm. I want the application to be run by a separate user so I've added the ...
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Is modifying a database on compressed ZFS slow?

Is modifying (mainly inserting new rows into tables with many indexes) a (PostgreSQL) database on a compressed ZFS slow (compared to an uncompressed ZFS)? I used a slow HDD backed by SSDs. Ubuntu ...
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The verify state file when doing fio with verify parameter

When doing: sudo fio --name=verify --trigger=reboot --trigger-timeout=2 --numjobs=1 --filename=/dev/sdb --rw=randwrite --verify=md5 it will generate a file: local-verify-0-verify.state Can I say every ...
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Doing fio testing and hotplug remove the SSD

When disk is in use, ex: doing fio testing ( random write ), remove the PCIe SSD at the same time. Should I expect there is no any I/O error since the system support hotplug?
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What's the verify function in fio when reading?

When doing fio test, we can set the verify parameter, for example, when doing write test, I think fio can verify the test by read the same location in disk to verify the write test is successfully. ...
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When is it beneficial to add -u to tr?

One of the arguments to the tr command is: -u Guarantee that any output is unbuffered. Under what circumstances is it a good idea to not buffer the output? e.g. should I use -u if I expect each ...
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Linux Mint stops responding for a few seconds

I recently got a new Desktop, which is quite the upgrade from my Laptop. Now I installed a fresh install of Linux Mint MATE 20.2. Now the performance isn't bad, but every so often there is a random ...
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Linux equivalent of Thread Director?

The 12th Generation Intel chips are rumoured to have "Efficient" and "Performance" cores. Apparently Microsoft's Thread Director, in Windows 11, takes advantage of them. What will ...
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1 answer
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How to get best performance on Windows VM without gpu passtrough?

I'm using OpenSUSE as my main OS on work laptop (Ryzen 5850U, no additional GPU), however I need to have working Outlook desktop app, since some of our company communications are encrypted using S/...
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2 votes
1 answer
118 views

In bash, is there a way to see how much memory .bashrc and any startup scripts are consuming?

In bash, .bashrc (and various other scripts) can load into memory at shell startup. These can be 10 lines long, but can be hundreds (if not thousands) of lines long. Each export will consume a tiny ...
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1 answer
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AMD Epyc 7452 having CPU base clock as max clock speed & not boosting to boost clock?

I have an AMD Epyc 7452 CPU on an ASRock Rack ROMED6U-2L2T board running Proxmox 7 a linux system and running cpupower frequency-info reveals the following: analyzing CPU 0: driver: acpi-cpufreq ...
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drive access got extremely slow

The HDD of my laptop got extremely slow all of the sudden (after a reboot). hdparm tells me that cached and buffered reads are both in the range of hundreds of kB/sec - that's slower than my ethernet. ...
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Does the worst PCIe MSI interrupt latency jitter over 100us normal?

I try to figure out the values of interrupt jitter in Linux, especially in the worst cases. Two testbeds are considered, one is Raspberry Pi 4B, the other is a high-end PC with an intel i9 CPU and ...
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6 votes
2 answers
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How do I diagnose random UI slowness and slow ssh connection initiation for several minutes after a reboot?

The boot sequence opens up Kodi in full screen. That comes up fine. But when I try to initiate an ssh connection it will often just simply time out. This lasts for about 10 minutes after a reboot. ...
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RabbitMQ, SCP in Linux dropping connections

In GNU/Linux I have an issue with an application I have made. It works in my development environment, most of the components running in dockers or natively, but it randomly (often, but not always) ...
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kworker hogging CPU after getting additional SSD - high acpi interrupts on gpe11, masking or disabling causes system freeze

Mine is a 7 year old Dell Inspiron 3542 (Intel i5), have been running Linux for about 5 years now. Recently I got an additional SSD fitted in the HDD slot and moved the HDD into the place of DVD Drive ...
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Linux cpufreq scaling_govenor "ondemand" doesn't work as expected

On a single-core i.MX6solo with 800 MHz, I have set three operating points at around 400, 500 and 800 MHz. At 800 MHz, the system load (according to top) is usually around 55%, every now and then ...
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3 votes
1 answer
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zfs send performance

I'm having an odd performance issue when trying to backup my zfs filesystems. I can tar the contents of a zfs filesystem at 100+ MB/s, but zfs send trickles the data at maybe 5 MB/s. The filesystem ...
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What is the best way to understand of the efficiency of my program other than load average?

Consider the following scenarios: I have only one process running on the machine and from resources like top gives 100% CPU usage which is good. I'm efficiently using the CPU. I have two processes ...
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Can someone explain the usefulness of Top's %CPU_ME and %CPU_OTHRS?

I'm looking at the top output and I notice there is a column for %CPU_ME and %CPU_OTHRS. The definition on the man page is: cpu_me - CPU time charged to me by other processes. cpu_others - CPU time ...
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3 votes
0 answers
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systemd niceness and scheduling configurations not effective in processes performance

My team inherited the care and maintenance of code for a service that runs three python scripts and creates processes which play a part in sending data from our product to another product. One process ...
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Diagnosing cause of a process using 100% CPU

I'm trying to diagnose a strange error occurring on a fairly stripped-down Celeron N2930 (quad core Atom) PC running a Qt Quick based Application on top of Debian 10 Linux 32-bit (think basically a ...
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Which Performance Co-Pilot metrics correspond to commonly displayed metrics?

I'm trying to use Performance Co-Pilot (pcp.io) to monitor performance on RHEL 7/8 hosts. A quick run of pminfo shows that I have other 2000 metrics available to me. I'd like to view the metrics that ...
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Server is slow, there's no workload, no apparent reason, only shutdown solves the problem

I manage a server that is now approximately 5 years old. It has Ubuntu Server installed. There had been a handful of times where suddenly it became super slow to the point it was basically unusable. ...
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Could a newer SuperMicro BIOS be impacting my Linux performance?

I've been seeing performance problems on a number of systems for a long time (high CPU usage) that only occurs on a specific few servers. Identical hardware, software, work loads. They're virtualized (...
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1 vote
0 answers
58 views

NVME slower on host than in VM

I first noticed some strange performance hits when I switched from Vagrant to Docker for my local development setup. After investigating why my databases were slower in this new environment, I came to ...
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1 answer
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Why is RAMFS much slower than Ram?

I have a 64GB DDR4 3200MHz memory installed on my PC. When I run sysbench, I get the following results: # sysbench memory --memory-block-size=1M --memory-total-size=10G run sysbench 1.0.20 (using ...
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2 answers
147 views

How do I reduce memory latency?

My environment is OpenVZ, using the 3.10.0-1160.21.1.vz7.174.13 GNU/Linux kernel. When executing vzstat, I am seeing the lat(ms) is very high (going to assume this means latency in miliseconds): This ...
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4 votes
4 answers
805 views

more swapping on RHEL8 than RHEL7?

we've been having a Linux application for quite some time (our journey started a decade ago with RHEL 4). We were recently running our app on RHEL 7.9 and are now moving to RHEL 8.4. We've always ...
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0 answers
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Could it be possible to throttle IOs using LD_PRELOAD?

I have a job on a managed Kubernetes cluster that is a bit IO intensive. Nothing crazy, it downloads about 1gb of data, writes it on /tmp folders, does some minor edits, compress and encrypts it, and ...
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Why integer division is faster than bitwise shift in shell?

I'm comparing performance of bash and dash (default sh in Xubuntu 18.04). I expect sh to be faster than bash I expect bitwise shift to be faster than division operator. However, I'm getting ...
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2 answers
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Does the speed of operations on a file (copy, move, remove) depend on permissions of that file?

Does the speed of operations on a file (copy, move, remove) depend on permissions of that file? If so, then how? Reason: need to constantly perform mentioned operations on many files. Will these ...
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