Questions tagged [optimization]
The optimization tag has no usage guidance.
60
questions
1
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0
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126
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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 ...
20
votes
1
answer
9k
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 ...
- 31.8k
4
votes
1
answer
1k
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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 ...
- 708
0
votes
1
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3k
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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 ...
- 29
7
votes
3
answers
1k
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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
...
user147505
2
votes
2
answers
1k
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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 <-- ...
user252842
4
votes
3
answers
116
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;...
- 9,764
4
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2
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4k
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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 ...
- 41
1
vote
2
answers
624
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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 ...
- 27.8k
1
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1
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372
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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 ...
- 11
6
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1
answer
667
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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 ...
- 1,046
2
votes
0
answers
396
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 ...
- 13.5k
1
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0
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203
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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?
- 129
1
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1
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674
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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 ...
- 113
2
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0
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332
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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 ...
- 13.5k