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Questions tagged [performance]

The speed at which a program runs

2
votes
1answer
63 views

filtering a large file with a larg filter

I want to extract all lines of $file1 that start with a string stored in $file2. $file1 is 4 GB large with about 20 million lines, $file2 has 2 million lines, is about 140 MB large and contains two ...
1
vote
0answers
16 views

How to diagnose the difference in OS performance between installation media?

I have two different USB sticks, a 128 GB Samsung and a 64 GB SanDisk. I used Gnome Disks to benchmark both of them and the Samsung one was supposedly better, it had faster read and write speed but it ...
0
votes
0answers
10 views

Is there any difference in performance when creating VM using default template vs custom snapshot in DO/AWS lightsail? [closed]

AWS Is there any difference in performance, when we creating instance in AWS Lightsail using your blueprints vs using custom snapshot? Example: AWS Using AWS Blueprint $result = $client->...
1
vote
1answer
26 views

Long time spent between grub2 menu, before kernel boot

I installed a minimal ubuntu (xubuntu-core). It works well, but boot is a bit too slow. Right after I make my choice in grub, the screen turns black and after around 15 seconds I see the kernel boot ...
5
votes
1answer
218 views

efficiently grep an interval of a sorted file

My file has millions of lines, resides in memory /dev/shm/tmp.file, is accessed by multiple threads, looks like this 831092,25a1bd66f2eec71aa2f0a8bb3d,/path/to/a/file 4324,8d83c29e4d8c71bd66f1bd66fs,/...
1
vote
1answer
29 views

How to analyze top command results: CPU & RAM consumption

I am working on ARM-based processor (OS version: Linux 3.4.35) and I need to analyze the processor's performance while some processes are running, by typing top command, I can see some statistics but ...
0
votes
0answers
18 views

Sizing of Samba Linux Server

Do you know any performance of sizing recommendations about Samba 4.7.1 ? For few informations : 2vCPUs / 1 Core 8GB of RAM 140 simultaneous Windows users / 250 at most / 20 NFS volumes mounted via ...
23
votes
8answers
2k views

Is piping, shifting, or parameter expansion more efficient?

I'm trying to find the most efficient way to iterate through certain values that are a consistent number of values away from each other in a space separated list of words(I don't want to use an array)....
0
votes
0answers
7 views

The nginx provide data download rate is not meet the iperf3 test

I use iperf3 test the IP, there gets 9.3G/s [root@localhost ~]# iperf3 -c 4.4.226.59 Connecting to host 43.224.226.59, port 5201 [ 4] local 4.4.226.69 port 57212 connected to 4.4.226.59 port 5201 [ ...
0
votes
2answers
58 views

Fast hashing in awk?

I find it cool that someone has written MD5 in AWK: https://kaworu.ch/blog/2017/05/23/implementing-md5-in-AWK/ Unfortunately that one is quite slow. I am looking for a fast hashing tool for AWK that ...
3
votes
0answers
32 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 ...
3
votes
2answers
67 views

Linux GUI becomes very unresponsive when doing heavy disk I/O - what to tune?

I have a device /dev/mydisk that is based on a stack of functionality: a LUKS-encrypted, software RAID-1. From time to time, I do a backup of /dev/mydisk contents to an external USB disk, which is ...
0
votes
0answers
28 views

Samba shared folder over openvpn very slow - Linux OS

Recently I've installed Ubuntu 18.04 and I've noticed that sharing a samba folder from a Linux server over a openvpn tunnel is very very slow. Tried to avoid using DNS, but still have no results. ...
0
votes
2answers
29 views

How to remove trailing CR quickly?

This is my source file, it dumps a database into a JSON and worked great with Debian wheezy: #!/bin/sh echo "Status: 200" echo echo { printf ".mode csv\nselect * from cfg;" | sqlite3 /home/ftproot/...
1
vote
2answers
31 views

Speeding up repeated python calls (or, alternatively, porting a complex regex to sed)

I am an academic medical physicist. I do experiments that generate a fair amount of data, and they are expensive to run. My university has a backup system that consists of a robot tape library in a ...
2
votes
1answer
37 views

Improving performance of Script Using find and exec [closed]

I have a script that iterates through a given directory and automatically compresses those that do not contain at least one file used in less than 30 days. Now, I am wondering if I could improve ...
0
votes
1answer
25 views

OS keeps getting slower the more time I leave it open

I recently decided against shutting down my Ubuntu machine in office because it took a lot of time to start it and then open all the applications that I would normally require. After leaving the PC ...
0
votes
1answer
19 views

mv command for many nonexistent files, does it wear off the destination disk at all?

I am trying to continuously move many files (~ 10 000 each minute) from /ramdisk to normal /ssd , but not all files are there. When the mv /ramdisk/file55 /ssd/file55 fails because source is not ...
3
votes
1answer
51 views

Why would NFS have lag after a minute of inactivity?

I am running a version 4 NFS server on a Salix server with kernel 3.10.17. I am mounting the NFS share with the command sudo mount -t nfs 10.0.0.150:/share /mountpoint on my client machine, which is ...
2
votes
0answers
70 views

Linux access windows share without loading to RAM

I have a laptop running an Arch-based Linux system and frequently need to access a windows share at my workplace. This is really annoying since it takes ages to load. Particularly, one folder is ...
22
votes
2answers
2k views

Why does the `updatedb` program run so fast?

Usually when I have programs that are doing a full disk scan and going over all files in the system they take a very long time to run. Why does updatedb run so fast in comparison?
1
vote
0answers
24 views

Performance issues on internal SATA device causing high load

I have a problem with the performance of my laptop. In fact I needed to install quite some things recently and the whole machine froze from time to time completely. First some general information: I ...
2
votes
1answer
76 views

USB 3.0 external hard disk only operating at 480 Mbit/s

When I attach my USB 3.0-Stick dmesg says: [ 3308.966755] usb 2-1.1: new SuperSpeed USB device number 5 using xhci_hcd [ 3308.987443] usb 2-1.1: New USB device found, idVendor=0781, idProduct=5583 [ ...
0
votes
0answers
29 views

Debian 9.5 takes longer to mount emmc than 8.7 did

I have been trying to chase down some boot performance issues for a little while now. Previously we were running debian 8.7 with 4.4.54 kernel. our start up time is systemd-analyze Startup finished ...
0
votes
0answers
25 views

How to calculate the throughput usage of AWS EBS volume

We have a hadoop cluster running on AWS EC2 instances. Configured 16T st1 volume in datanodes for HDFS usage. We need to understand, what is the maximum throughput hitting on this st1 volumes. Since ...
1
vote
2answers
39 views

compare memory performance of two machines (low buffers vs high cached)

I'm trying to compare the performance of two machines that I have. I have in both of the machines a database that was installed with the same settings. Both of the machines have the same amount of cpu(...
1
vote
1answer
37 views

Zsh Performance: Should I create scripts or just add functions to a file I source in .zshrc?

I use a lot of little zsh functions. I have been adding them to a single functions.zsh file which I source in .zshrc. If they are created as scripts, or autoloading is used, will that improve speed? ...
0
votes
2answers
55 views

What exactly does `ps -p PID` do that `ps -q PID` does not?

According to man ps: -p pidlist Select by PID. This selects the processes whose process ID numbers appear in pidlist. Identical to p and --pid. -q pidlist ...
0
votes
2answers
96 views

Is there a way to predict or count the number of page faults?

I am working on hardware performance counter (HPCs) and I seek to use these counters to measure some events accurately. I have found that the non-determinism in hardware performance counter (...
2
votes
1answer
162 views

Why do terminal emulators still have screen flicker?

Why are there still visual artifacts when terminal emulators draw text-based applications? This on recent computers that render 3D games and GUI windows including anti-aliased vector fonts with no ...
1
vote
1answer
129 views

Send sar series to grafana [closed]

sar of sysstat package produces a lot of useful information about system usage regarding various resources; My question (since after a brief query I was unable to find a useful suggestion / solution) ...
0
votes
1answer
18 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 ...
-1
votes
1answer
162 views

/proc/sys/vm/drop_caches values

I want to know what values are possible for drop_caches, and what the meaning of that values are. For example: echo 3 > /proc/sys/vm/drop_caches What does number 3 mean? Are the numbers, 1, 2 or ...
0
votes
1answer
44 views

Disk I/O Information

I want to get the read and write, service time, queue length and wait time of my disks. the OS is CentOS 6. I use iostat. when I run this command: iostat -x -d /dev/sda the output is: ...
0
votes
1answer
42 views

Performance of active port - netstat

Below command [root@machine1 output]# netstat -s --udp IcmpMsg: InType0: 371137 InType3: 296 InType8: 386843 InType11: 4 InType13: 141 InType15:...
3
votes
2answers
103 views

Disk Performance Monitoring [closed]

I have a physical server with 2 disks, sda and sdb. I want to monitor their I/O and performance. The monitoring element has 3 types: ops, sps, and bps. What are these and which one is better to ...
0
votes
1answer
24 views

Is opening new tab equivalent to opening new window?

Is opening new tab in the terminal window is equivalent to opening a new tab in terms of resources? I need to run 16 scripts in parallel. I do not know whether opening tabs or new terminals is the ...
5
votes
1answer
87 views

System lags when doing large R/W operations on external disks

I am having some issues with system-wide latency/lagging when doing large disk imaging operations on an Ubuntu 18.04 system. Here's the system specs: Processor: Intel Core i7 (never near capacity on ...
0
votes
1answer
115 views

What are the differences between qperf and ping test latency results?

I am wondering what are the differences between qperf and ping tests latency results. In terms of measuring latency between two servers which tool result could be considered more accurate? ping: ...
0
votes
1answer
47 views

Why is my very old USB2 Harddisk faster than expected?

http://web1.heissa.de/usb2_speed.pdf From the spec, I would expect a max. write rate of 60 Mbyte/s. But today a simple test told me it‘s 226 MB/s. Is it possible that this is a trick of kernel 4,18 ...
2
votes
2answers
113 views

How to debug program latency?

I'm trying to run amsynth on a rpi. Latest version of raspbian, fresh install. I tested amsynth on my x86 desktop and it works great, no latency. On the rpi however, I get a delay of around 1 sec ...
0
votes
1answer
223 views

How to pinpoint what process uses the disk using NMON on AIX

On an AIX 7.2 machine I need to investigate what is causing daily slowdowns between certain hours, and after analyzing the .nmon files using the nmon analyzer excel I've found that indeed the Disk ...
2
votes
0answers
36 views

How important is os-variant for kvm configuration?

When searching the internet one can always read that specifying os-variant is important so KVM can optimize the guest system. Nowhere did I find an article, manual or documentation stating how ...
3
votes
2answers
84 views

Why is it slower to write the same data to a *larger* pre-allocated file?

I am writing 4 * 4KB blocks to a file. It is consistently around 50% slower if I have used fallocate() to pre-allocate the file with 9 blocks, instead of only pre-allocating the 4 blocks. Why? There ...
0
votes
1answer
75 views

Advantages of pageable memory

While installing a Nessus product I came up with the following statement, Generally, a Nessus Agent uses 40 MB of RAM (all pageable). Here, What they tried to mean by all pageable ? As I ...
0
votes
0answers
26 views

How to see write speed with iostat?

I am trying to monitor disk i/o in CentOS 7. Using iostat I can see accurate numbers for sdb, which is my boot drive. But for sda I can only see read speed. Write speed always shows zero. sdb is a ...
2
votes
1answer
292 views

Raspberry Pi3 with Kodi runs very very slowly [closed]

My rPI3 runs very slowly with Kodi on it. I installed Kodi in March 2018 through LibreELEC. Kodi is at its latest version. Any suggestion? The bootup time is fairly fast; it boots up in less than a ...
2
votes
3answers
55 views

Are there any practical reasons for setting a maxlogins limit for users in limits.conf? What are the benefits?

Why should I set a maxlogins limit in /etc/security/limits.conf? In other words, are there any performance-related and security-related benefits to be gained? I have only three users on my machine, ...
3
votes
1answer
129 views

effect of file organization on efficiency of file access

The organization of files in a directory structure can markedly impact the efficiency of file access (ref). For the sake of example, consider two directories, A and B, each containing 10^6 files, ...
0
votes
1answer
25 views

can we View the contents of the atop log files that sent from remote machine on local machine

on remote machine we have the following atop files ls -l /var/log/atop/ total 1634632 -rw-r--r-- 1 root root 127992086 Aug 30 01:49 atop_20180829 -rw-r--r-- 1 root root 262277153 Aug 31 00:00 ...