Questions tagged [performance]
The speed at which a program runs
1,024
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hostapd: slow performance unless android phone connects
I have an host computer, set up with hostapd as access point and dnsmasq for DHCP server. I'm running under ArchLinux, with Linux kernel 6.1 (as I'm on an embedded ARM board which only supports up to ...
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Debian - Terrible Performance on MacBook Pro. LUKS Related?
Two days ago I did a fresh install of Debian 12 stable + Xfce on my Late 2013 MacBook Pro using LUKS for full-disk encryption. Performance around the OS has been incredibly poor. My CPU is hardly ...
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How to reach optimal speeds with rsync?
I am using rsync to sync around ~2TB of data to a mechanical HDD-5400RPM. It's taking way too long.
How can I improve the sync and check speeds to get as close as possible to maximum/optimal?
Here is ...
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Encrypted LUKS fs inside a file: sparse or not?
I have a LUKS encrypted file filled with around 160 GB of data
that I use a lot. For safety, I created the file with 400 GB.
That is, of course, a lot of wasted space.
So I switched to a sparse file,...
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Why is `mv -f source target` so much slower than `rm -f target && mv source target`
I got a case where I need to overwrite some file with another and noticed a very significant slowdown when using "mv -f" if the target already exists and is being read. More specifically, ...
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Horrible performance when downloading from CIFS mounted drive
I have recently wanted to mount a remote CIFS drive. But i have run into one major issue. The speeds are amazing. Uploading is about 220Mbit/s.. However, downloading has speeds of 5Mbit/s.. Which is ...
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High CPU Usage and lag in LinuxMint: performance Issues and Solutions
I open some programs (maybe limited to games, or maybe the problem lies deeper) on my Linux Mint, and when I check their status using the top command in the terminal, I see that they completely use 3 ...
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Simulate slow disks in KVM to see effect of LVM cache in test setup
I'm setting up a Linux system in KVM (QEMU) to test the effect of adding a writeback LVM cache on a fast disk in front of a logical volume that resides on a set of very slow disks (a RAID1 LV). This ...
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Why only LLC miss ratio increase?
On my server, I have a latency critical (LC) task running on NUMA0. To increase utilization, I have also deployed some best-effort (BE) tasks on the same NUMA0. Furthermore, I have enabled some ...
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Why I see different cpu-migrations from top and perf stat?
New to system performance analyze.
I am curious on how CPU affinity affect kvm virtual machine.
So I try to bind vm's vcpu to physical cpu to improve vm's performance.
find the pid of the vm(ecs-...
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CPU running well under maximum frequency
I use my computer for very CPU intense simulations, but no matter what I do the actual CPU frequency wont ever come close to hardware capacity.
I have an i9-13900K, which maximum CPU freq. is 5.8GHz. ...
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Intel turbo boost all core clock speed in practice
My understanding is that Intel's quoted "max turbo boost" speed is only guaranteed when a single core is active, and that when all cores are active, the clock speed could conceivably fall to ...
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How to diff two files in bash efficiently?
I have two files containing the similar pattern:
cmd1 [cmd2 {xx/xx[7] x/x[0] ...}] cmd3 [cmd4 {xx/x[12] ...}]
cmd5 [cmd6 {x/x[1] xx ...}]
I don't need to consider all the cmds in two files. Only need ...
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How to improve performance of unicast to broadcast UDP packet transformation on OpenWrt?
Background
We have some devices sending unicast UDP packets which we want to receive on multiple computers by transforming those packets to broadcast. We can't make any changes to the devices sending ...
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why is all this swap space being used?
I have a Debian box, where I am doing some data recovery using ddrescue on a sata ssd. The process has been running for 24 hours, and has 24 to go (at least)
in any event, the PC has 16GB ram, and ...
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Is there a way to make window either spawning or changing from tiled to floating take the earlier size and place?
I know that I can tell bspwm to spawn windows in specified desktop or monitor in tiled mode or in certain shape and position via floating mode. But I am looking for the window to remember its previous ...
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How do I compare performance of two linux kernel images running on QEMU?
I have built a tracing utility for the Linux Kernel and am testing the same on QEMU. I want to compare the performance of the kernel with and without the tracer. How do I go about doing this?
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136
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Remove subdomains or existing domains
I have a list of domains, a sample is:
account.google.com
drive.google.com
google.com
bgoogle.com
yahoo.co.uk
stats.wikipedia.org
media.wikipedia.org
files.media.wikipedia.org
bible.com
I would like ...
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ZFS dataset encryption on top of LUKS
There has been discussions about using ZFS on top of a LUKS-encrypted partition vs. using ZFS's native per-dataset encryption. However, they are always presented as either-or.
My question is about ...
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Monitorix disable subgraphs
I have a Monitorix service running on my system. By changing y/n values in the graph_enable section I can enable and disable certain graphs, however, there are subgraphs for almost every main graph e....
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SSH hangs/disconnects unless using `-v` option
I have a raspberry pi setup. When connected over ethernet ssh sometimes hangs, but generally works. When connected over wifi ssh is extremely choppy (8/10 connections fail, if I connect it drops ...
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Why is 7-zip much faster than other LZMA implementations in Linux?
Until now, I used to backup my data using tar with one of the LZMA compression options (--lzma, --xz or --lzip)
I recently noticed that 7-Zip has been ported to Linux in 2021 (https://www.xda-...
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What's the expected overhead of a passthrough device mapper?
I'm trying to establish a baseline throughput overhead for a passthrough device mapper; i.e. a device mapper that does nothing. Roughly following benchmarking procedures from Cloudflare, I'm measuring ...
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275
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Is it safe to add LVM cache device to existing LVM volume group while filesystem is mounted?
I have an existing LVM volume group with a 10 TB logical volume mounted as an ext4 system which is actively in use.
Is it safe to run the command lvconvert --type cache --cachepool storage/lvmcache-...
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How to get scheduling latency with Ftrace in Linux?
I am working on an embedded Linux (kernel-5.10.24) system where ftrace is enabled but NO perf.
I checked the tracefs in my system, and got followings,
# ls /sys/kernel/tracing/events/sched/ -l
total 0
...
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Laggy PC with Kernel 6.5 and AMD 5500U Lucienne
I am currently facing a problem with my Lenovo E15 laptop (AMD Ryzen 5500u "Lucienne" processor) and the kernel 6.5. (Xubuntu 22.04)
Maybe three weeks ago,
I noticed that my computer was ...
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answer
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Solving the USB drive/mass storage stall issue
Sadly the issue reported and described here: Pernicious USB-stick stall problem. Reverting workaround fix? and Is "writeback throttling" a solution to the "USB-stick stall problem"?...
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How to enable PMU in WSL2?
I am using WSL2 in Windows11 as my Linux host.
Now I want to run perf in this WSL2, but I failed to do that with following errors.
# uname -a
Linux testhost 5.15.133.1-microsoft-standard-WSL2 #1 SMP ...
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Is it possibel to enable X86 PMU in QEMU emulation mode (without KVM)?
I am trying to run perf in my Linux system, but WSL2 and virtual-box 6.1 do NOT detect the hardware PMU in system.
So, I installed qemu-system-x86_64 in Linux VM, and tried to run QEMU in emulation ...
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Fedora slow boot time
I recently removed Windows from my machine because I would like to adopt Linux as my main OS, specifically Fedora. Following are my machine specs:
The system works pretty well, but the problem is ...
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A simple memcpy loop with stride of 8-16-32 Bytes, no L1 cache misses, what stalls backend cycles?
I am trying to understand the CPU cache performance in a single producer single consumer queue algorithm, but cannot pinpoint the cause of performance degradation in some cases. The following ...
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Differences between qemu-i386 and Linux IA32 emulation
On x86-64 Linux, there are two options for running 32-bit applications: one can be built into the kernel itself via the option CONFIG_IA32_EMULATION (normally on for most kernels), and the other is ...
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fork() is very slow
I have a Linux server running Ubuntu 18.04 on a VM. Executing any task like ls -l or w frequently takes several seconds to finish. strace -c ls -l says ls only takes a few milliseconds, but running ...
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How many files in a directory is too many for ext4?
I wrote a Golang program to measure how long it takes to create 100 new files and read 100 existing files in a directory with 2k files vs a directory with 200k files:
// Create 200k files in one ...
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Undertanding the performance of replication in distributed storage
I have a bit of a struggle understanding the performance when using replication in distributed storage solutions (Linstor/DRBD in my case).
I have 3 storage nodes, 10 NVMe each. Each NVMe has a write ...
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1
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43
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Why do /dev/ramX devices have all 0's in /proc/diskstats?
Is there away way to turn on IO accounting for /dev/ramX block devices in Linux? I already tried echo 1 > /sys/block/ram1/queue/iostat but it did not work.
Notice that all devices have stats except ...
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there is a performance gap between distros? [closed]
I am new to linux. Now i have tried a bunch of distros, like debian ubuntu fedora and arch. I was wondering which distro offers the best performance. For reference my machine is laptop(huawei matebook ...
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How can a different controller explain this I/O?
My new NAS has 5 disks. They are all same model.
sde is connected to the controller on the motherboard. sda-sdd is on the raid controller.
Run 'pv /dev/sd[cde]' in parallel:
Device rkB/s wkB/...
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Which is the trigger of OOM killer, free or availaible memory in Linux?
I am working on an embedded Linux system which is on SOC platform.
I have 2 machines ran the same memory workload, and I got following memory output.
Machine 1.
total used ...
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what's the fastest way of writing data to ffmpeg for video streams?
I'm live streaming my x11 screen to a v4l2 webcam device (/dev/video0) with FFmpeg through stdin :
ffmpeg -re -probesize 32 -analyzeduration 0 -i pipe:0 -s 1280x720 -vf scale=1280:720 -preset veryfast ...
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Does NUMA need to be explicitly enabled before calling kernel API functions?
I'm converting a C++ application (running on Ubuntu) from single-socket to multi-socket. I would like to change the memory allocation to be NUMA-aware.
I know the application will need to call C API ...
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Optmization and tuning Linux Server (Mediaserver)
I rebuilt a server, specifically a mediaserver, based on debian 12 stable (kernel 6.1).
CPU: i7-6700K(no overclock)
RAM: 16GB DDR4 (dual channel)
NIC: 2 of 2.5Gbit (bonding balance-tlb) (MTU bond0: ...
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Surprise in measuring UBIFS on NAND performance in Linux
I am working on an embedded Linux system (Linux-5.10.24), and there is a raw NAND FLASH as storage device on which UBI/UBIFS is used as file system.
Now I am trying to measure and compare the UBIFS ...
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Latency on pselect caused by other user space processes
I have the following pre-condition on Linux:
I'm using a process to read serial data using pselect on a serial device /dev/ttySX.
Data comes in at a stable frequency of 400 Hz.
To optimize latency of ...
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How to measure mmap I/O latency?
I have an application which appears to be slowing/blocking at the same time there's a lot of disk I/O going on, so I suspect it's I/O operations within the application which are blocking. I can't ...
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Gather CPU utilisation or different workloads
I am trying to figure out for different workloads (CPU intensive, high DB IOPs etc), which compute series of cloud VM would be ideal.
In order to do that I need to be able to get the CPU utilisation. ...
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Pop Os taking long time to boot and start certain programs
I apologize that this question has been asked before. I looked at the answers on those questions but am still struggling. I have recently switched to Linux after using Windows for decades.
I've been ...
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Http outperformed Http2 ,why, please help me to figure out?
I'm currently conducting performance testing on my NGINX web server container and I'm encountering some unexpected results. My tests show that HTTP performance is outperforming HTTP/2, despite SSL and ...
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85
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Can some command or script subtract lines in one file from another faster than grep?
I have a shell script that runs regularly and the following part of it causes a slowdown.
grep -v -f RemoveTheseGoodIPs.txt FromTheseShadyIPs.txt > RemainingBadIPs.txt
It works. It just takes 156 ...
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2
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Are Intel or AMD processors generally regarded as "better" for Linux [closed]
Are there any differences between Intel and AMD processors in how Linux runs? Specifically in terms of performance, optimizations, and driver support?
To simplify things, I am just talking about the ...
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