Questions tagged [optimization]
The optimization tag has no usage guidance.
54
questions
0
votes
0answers
17 views
Pipewire using 2x processes when idling
I recently had my BT headphones stutter and cut out and realized that during CPU intensive processing, pipewire is dropping frames. My overall goal, then, is to streamline processing to make that ...
0
votes
0answers
8 views
faster log handling
I have a system that writes log files. The files come in sequentially, but a single log has 3 or more files. The first file will indicate START, the next file(s) will indicate INFO, and the final ...
1
vote
0answers
44 views
Can't compile linux kernel with -Og/-O0 option for debugging purpoces
Having custom hardware running embedded Linux (OpenWrt) like a charm. CPU - is IMX6ULL (ArmV7) so it is supported by Jlink to debug over JTAG interface.
Starting GDB server and step by step debugging ...
0
votes
0answers
52 views
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 ...
1
vote
0answers
79 views
Is jq internal sort slower than GNU sort?
While filtering through this json file I did a benchmark and found out utilizing jq's internal sort and unique method is actually 25% slower than sort --unique!
Command
Mean [ms]
Min [ms]
Max [ms]
...
1
vote
2answers
133 views
How to Build Latest HandBrake on linux with FDO (PGO) + LTO?
Passing CFLAGS and CXXFLAGS to a HandBrake build for the latest version (v1.3.3 at the time of this writing) will work until you add -flto which will FAIL the whole build.
How to build HandBrake with ...
0
votes
0answers
99 views
How to add flto and pgo to linux kernel build?
As the title states, I'm wishing to try out the latest stable mainline kernel by building it with lto and pgo with O3. How do I go about doing this and be confident that it is actually built in the ...
1
vote
0answers
51 views
How can I frequently update a file without harming my disk?
I've got an i3 install on a laptop with an SSD. Currently I have it configured to save the WM layout on many different events. The tool that I'm using to do this is built on Python, and I'm just ...
0
votes
0answers
48 views
How to compile kernel without optimizing scheduler
I have developed an application demonstrating priority inversion in linux kernel and now I want to prove it by capturing certain context switches using kgdb. I have working setup to debug kernel on ...
-1
votes
2answers
34 views
Optimize time when creating archive
Currently I am using the following command to create an archive with files older than 7 days:
find /var/tunningLog/ -type f -mtime +7 -print0 | tar -czf "/var/tunningLog/$(date '+%Y-%m-%d').tar....
0
votes
1answer
57 views
Optimal command-line search inside a sorted text file
Let's say I have a text file with billions of text lines sorted alphabetically, like
Bar=10
Foo=6
Naz=42
How can I search for the line starting with Foo in the most optimal way (the file contains ...
3
votes
1answer
131 views
Is there an equivalent to Jason Randolph's Super Duper mode vim re-mapping for Linux?
I'm very interested in moving from my Mac to a Linux system. The main barrier is my dependence on Jason Rudolph's Keyboard. Specifically, I need an equivalent to (S)uper (D)uper Mode. Super Duper ...
1
vote
1answer
63 views
How to pipe output of command to two separate commands and store outputs
I have a really long command that runs over a huge file and I am forced to run it twice which doubles the time it takes to run.
This is what I am doing at the moment:
x=$(command | sort -u)
y=$(...
2
votes
1answer
67 views
KSM / MADVISE : Init & usage in standard desktop environment
Running a 4.19 linux kernel + couple of patches RT oriented + occasionally running a couple of processes SCHED_RR (for "pro"-audio purposes)
CONFIG_KSM set in the kernel and ksmd running, I ...
0
votes
1answer
1k views
Build the Linux kernel without gcc optimization
I follow one of many tutorials found on Google results to build and debug the Linux kernel with gcc and kgdb/gdb. And I end up by discovering that is all waste of time. Since I can't compile the ...
0
votes
1answer
15 views
Timing desktop environment initialization
Is there a way to time desktop environment initialization and perhaps identify delaying candidates?
-4
votes
1answer
149 views
Why don't BSD kernels use likely() unlike Linux does?
As pointed out in an answer, there's some use of similar hints to compiler in say, FreeBSD and OpenBSD, but those hints coverage of Linux kernel code is a few magnitudes higher. It might make sense to ...
0
votes
2answers
72 views
How to resize images on sequential functions?
I am trying to:
change the format of my images,
then resize their height and width of 40%
then optimize their quality to 35% max of the source and the total size of the image to 35% of the origin.
...
0
votes
0answers
27 views
Optimize raid drive for disk read
I have a Hardware RAID10 setup at home for my home server. I run a Plex Media server and a Nextcloud cloud server for my family at home. My concern is, that when I am downloading a movie (heavy disk ...
2
votes
1answer
508 views
Can I compile Linux kernel with -Ofast?
I want to know if compiling the Linux kernel with -Ofast is:
Worth it.
Supported (what level of optimization do the kernel writers take into account?)
Secure.
The question arised because ...
-1
votes
1answer
213 views
What are all the possible optimizations I could apply to a new build of Gentoo? [closed]
With the assumption that I'm using hardware with a very modern CPU (9900K), what are all the possible optimizations I could apply to a new build of Gentoo in order to gain the best possible ...
1
vote
0answers
313 views
how do I emerge gcc 9 on gentoo without creating too many processes?
I am stuck on building gcc 9 with lto USE flag, because it is creating over 30 lto processes when I try to do so. At this point, I have to reboot my PC. I think it may have to do with the new lto ...
-1
votes
2answers
873 views
Is it safe to disable clamscan and clamd services on linux server
We have a dedicated CentOS server with 8 CPUs. We often observe clamscan and clamav taking too much CPU. I have heard experts saying linux doesn't require an antivirus. If that is true, is it safe to ...
1
vote
1answer
238 views
Speed up random sort and delete (rm) for multiple directories
Running MacOS in a terminal which is essentially BSD, hence posting my question here instead of askdifferent. I want to trim my image dataset down in subsequent steps, by deleting files randomly. Some ...
4
votes
0answers
997 views
Compile a library aiming to reduce size as much as possible
I have to 'squeeze' all the needed code to run ldaps on an embedded system. So the 3 MiB of lybcrypto and almost 700KiB of libssl are way too much.
I'm now experimenting on ldapsearch because reading ...
2
votes
0answers
83 views
Nested Virtualization [closed]
I want to deploy openstack with nested virtualization enabled. Here is the scenario, on physical machine (Ubuntu 16.04) I have 2 VMs running,
1. kvm01 and,
2. cmp001
Kvm01: has 7 VMs up and running ...
19
votes
1answer
7k views
Why can the kernel not use SSE/AVX registers and instructions?
This post from StackOverflow has this,
In some environments there there is a restriction on certain instructions or using certain registers. For example, in the Linux kernel, use of SSE/AVX or FP ...
4
votes
1answer
696 views
Fastest way to count zero bytes on a partition
My root and home partitions are LUKS-encrypted. I wish to have discard/TRIM enabled on them (I'm aware of security implications). If my understanding is correct, this should result in discarded areas ...
-1
votes
1answer
2k views
Why configure/build gcc takes much more time than apt-get install gcc [closed]
Wander to make some modification on libgomp (gcc's OpenMP runtime library), I downloaded the source code of GCC8, and tried to configure/make the whole compiler.
The configuration phase terminated ...
7
votes
3answers
1k views
Do file descriptors optimise writing to files?
Is it equivalent to have commands print to a file directly, as opposed to writing to a file descriptor?
Illustration
Writing to file directly:
for i in {1..1000}; do >>x echo "$i"; done
...
2
votes
2answers
716 views
Set usb flash drive as non rotational drive
I'm trying to optimize the IO schedulers and to use a proper scheduler for rotational and for non rotational drives (different).
When I run:
cat /sys/block/sd*/queue/rotational
I get:
1 <-- ...
4
votes
3answers
100 views
Script optimisation to find duplicates filename in huge CSV
I have several CSV file from 1MB to 6GB generated by inotify script with a list of events formatted as is:
timestamp;fullpath;event;size.
Those files are formatted like this :
timestamp;fullpath;...
4
votes
2answers
3k views
How to force a Thinkpad to draw charge from internal vs external battery?
My T450s Thinkpad has two built-in batteries--one hot-swappable and one inside the laptop. Lenovo calls the former "external" and the latter "internal". When not plugged in, the external battery ...
1
vote
2answers
462 views
Does zgrep reuse recently uncompressed files?
I am calling zgrep over *.gz files in a for loop in one directory.
As the log files are huge (about 1GB each, and about 30 files), the command is taking a long time.
I see several uncompressed files ...
1
vote
1answer
244 views
How do you specify a blkparse format specifier that also suppresses summary
When using the live mode, I do:
blktrace -d /dev/sdc1 -o -|blkparse -f '%a %c' -i -
I just want to limit the displayed data to 'action' and 'cpu id'.
Instead I get the summary and all the usual ...
6
votes
1answer
545 views
How to create a configuration to only connect to WiFi if signal is ≥ 30 %?
Is there any chance to create a configuration that does the following job?
Only connect to available WiFi if it's signal is stronger than 30 %
At many places, I stay in the border area of barely ...
3
votes
0answers
297 views
How do backreferences slow down regular expression search?
Let's say I have a text file with 20 chars per line like this:
wertzuiopasdfghjkl<
asdfghjkl<yxcvbnm,.-
<yxcvbnm,.-123456789
1234567890QWERTZUIOP
QWERTZUIOPASDFGHJKL<
and so on ...
and ...
1
vote
0answers
179 views
Optimal value for make -j <value> [duplicate]
What is the optimal value of the -j flag for make ? I know that all my source is free of errors.
Is it the number of cores? Or the number of logical processors?
1
vote
1answer
569 views
How to increase no. of nfsd threads in WD my cloud (nfs server)? for better performance
There are only 8 default nfsd threads available in WD my cloud, this no. is not sufficient for my requirement. I want to increase default nfsd threads to 20 threads. For this I first connected with ...
2
votes
0answers
255 views
Is there a linux interface for arm cp15 register access?
For performance optizimization I should be able to switch bits in ACTLR register of the cp15 unit. I've done stuff like this before in bare metal projects, but from linux user space I can't execute ...
2
votes
0answers
149 views
selinux user add becoming progressively slower
I've written a service that configures a machine with selinux users who can manage a single port. I'm trying to pre-seed that machine with 1000 users, but selinux is crawling to a halt around user ...
12
votes
1answer
620 views
How does ksh93 avoid forks in command substitution
Given
cmd='fun(){ echo "$@"; }; fun $(fun $(fun hi))'
shells tend to need to make 2 forks to make it happen
strace-f(){ strace -f "$@" 2>&1; };
for sh in dash bash zsh ksh; do
printf ...
16
votes
5answers
23k views
Compress a large number of large files fast
I have about 200 GB of log data generated daily, distributed among about 150 different log files.
I have a script that moves the files to a temporary location and does a tar-bz2 on the temporary ...
6
votes
1answer
1k views
SSD optimization
I know this has been discussed many times, but there are a lot of different opinions across the internet which optimizations are good for SSDs (and whether to use them). Also the technology has ...
1
vote
2answers
2k views
Optimize/Replace 'find' command
I am looking to optimize this find command. We have to move a bunch (sometimes almost a million) files to a directory for further processing. We are looking for a way to increase the speed of this ...
4
votes
2answers
250 views
How do I write a script to automatically optimize all the PNGs in my MediaWiki images directory?
I have MediaWiki 1.25.2 installed on my 64-bit Debian 8.1 VirtualBox machine and I'd like to be able to upload the images/ directory from this installation to my DropBox. Being a cheapskate I'm trying ...
1
vote
0answers
116 views
VNC rendering is all fragmented
I have my VNC server so configured, that it requires me to establish an ssh tunnel and connect to it on localhost:1 with my vncviewer. Now the connectivity seems to work fine but the rendering of the ...
5
votes
4answers
30k views
How to calculate the memory consumed by a "C" program in linux
I have written two C programmes
one is using function pointer, and
the other without function pointer.
Now i want to know the memory consumed by the two programmes , to see how memory can ...
1
vote
0answers
432 views
What are the consequences of disabling nmi_watchdog?
My aim was to improve battery life for my laptop.
I have already applied some advised modifications like enabling ALPM, and adding pcie_aspm=force drm.vblankoffdelay=1 i915.semaphores=1 at grub ...
2
votes
0answers
398 views
Ubuntu Bootchart - How do I actually interpret this chart?
I'd like to start obsessing over optimizing my Ubuntu boot time, but I've searched online for multiple days—and only have a vaguely more coherent idea of what I'm looking at.
Here's my bootchart. I ...
