Unix and Linux Stack Exchange
Unix and Linux Stack Exchange

Questions tagged [latency]

35 questions
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Why would anyone choose not to use the lowlatency kernel?

I can't find any good information on the rt and lowlatency Linux kernels. I am wondering why anybody would not want to use a lowlatency kernel. Also, if anyone can tell what the specific differences are, that would be great too.
Startec
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Do kernel threads seem to interfere with full tickless mode?

I'm trying to disable local timer interrupts for low latency. I have full tickless mode enabled in the kernel config and I have the boot parameter nohz_full set for the cores in question. However when I look at the interrupt count through…
Nathan Doromal
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Low latency vs normal kernel?

I am new to this world, and I want to make and record music with my new Linux installation, as I have found marvellous applications. I have seen some youtubers recomending to install the linux-lowlatency package. Is it going to somehow delete my…
ivanovitx
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How to keep a local directory automatically synced with a remote, without latency issues?

I develop a git-tracked codebase that has a lot of files. This code must be run on a remote machine. So every time I make a change locally, I must then sync it to the remote and run the new code on the remote. I want to eliminate the manual sync…
Donentolon
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Why would SSH freeze for minutes at a time when other traffic is unaffected?

I've noticed when I SSH into a remote machine over a slow link, SSH seems to "stick" after a relatively large amount of data is transferred. For example, typing text over the link is fine, but running ls /etc will freeze the connection for a few…
Malvineous
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How can I determine if a latency is due to a driver or the scheduler?

Using an oscilloscope and toggling some pins I sometimes see latencies of 1-2 seconds from when an 8-byte UART packet is transmitted to when a blocking read returns. The packets are 1 second part with a few milliseconds of jitter. I also measured…
Kenny
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How to find out a CAS latency on my SODIMM DDR3 module?

I have a HP Probook 6470b laptop with HP MBO 179C and Intel mobile HM76 chipset. I would like to find out a CAS latency of my DDR3 memory module without opening the laptop. I was told that the SMBus should show up as device 00:1f.3, but it is…
Hrvoje T
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strange issue, worst network speed and worst ping latency on linux

I cannot explain this, I will start by listing these speed test results this one is the linux host running mxlinux latest version this one is the windows 10 running inside vmware on the same computer I'm trying to figure out why it's THAT bad on…
Fredou
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Linux Completely Fair Scheduler and sched_latency_ns

I thought I understood CFS but... The scheduled latency is the time that in which every runnable process can expect to get a share of the processor. In the Linux Kernel code it gives: (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) Which for…
Mike James
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Linux: How is the input latency of a Wacom tablet distributed among the various software- and hardware components?

Say I have the following setup: Linux Kernel input-wacom kernel driver xf86-input-wacom X11 driver Wacom tablet How is input latency distributed among these various components? Are there any bottlenecks? If one wanted to make software patches to…
Árni Dagur
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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 between sending a midi command (using vkeybd) and…
cat pants
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High network latency after incoming UDP bursts

This has been crossposted to https://forum.rocketboards.org/t/high-network-latency-after-incoming-udp-bursts/1266 I have an application sending UDP packets over a RAW socket (defining ETH, IP and UDP headers manually), with up to 1 gigabit speed…
Stephan Kempkes
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How to tune Linux kernel to try to keep free RAM ready?

I have a system with very spikey memory usage and lots of disk activity. As such, I'd like to have files in the cache as much as possible but I'd like to have enough free RAM ready to go to quickly respond to user mode processes that require more…
Mikko Rantalainen
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How to change the default BDI `max_ratio` and/or `min_ratio` for all devices?

I'm using a system with multiple storage devices with different write throughput. As explained in question Why were "USB-stick stall" problems reported in 2013? Why wasn't this problem solved by the existing "No-I/O dirty throttling" code? Linux…
Mikko Rantalainen
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Add extra latency on top of existing tc qdiscs

On a system with an existing multi-stage qdisc setup, we need to introduce extra latency (at least fixed, but fixed with a small variation would be a nice option to have). The canonical way to do this on Linux is to use the netem qdisc. However,…
mirabilos
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