18 Feb
2013
18 Feb
'13
9:36 p.m.
If a better response time from the kernel is something that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ? Any drawbacks ? I presume the
Audio-oriented Linux distros do have lowlatency kernels by default, do
they ?
18 Feb
18 Feb
9:43 p.m.
Il 18/02/2013 21:36, jonetsu(a)teksavvy.com ha scritto:
If a better response time from the kernel is something
that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ? Any drawbacks ? I presume the
Audio-oriented Linux distros do have lowlatency kernels by default, do
they ?
You can find some information here:
http://www.jackaudio.org/realtime_vs_realtime_kernel
I don't use a RT kernel, I manage to get good low latency with the
hardware I have.
--
Federico
9:44 p.m.
On Mon, Feb 18, 2013 at 3:36 PM, <jonetsu(a)teksavvy.com> wrote:
If a better response time from the kernel is something
that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in Linux
Mint and Fedora) If it is So Good, what are the arguments for not having a
lowlatency kernel by default ? Any drawbacks ? I presume the
Audio-oriented Linux distros do have lowlatency kernels by default, do they
?
Ubuntu Studio uses low-latency kernel by default, and I am pretty sure
some of the other multimedia distros do also.
--
Brett W. McCoy -- http://www.brettwmccoy.com
------------------------------------------------------------------------
"In the rhythm of music a secret is hidden; If I were to divulge it,
it would overturn the world."
-- Jelaleddin Rumi
9:57 p.m.
On Mon, Feb 18, 2013 at 3:36 PM, <jonetsu(a)teksavvy.com> wrote:
If a better response time from the kernel is something
that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ?
latency and bandwidth are opposing goals. server oriented (compute-based
or storage-based) systems want to have the highest possible bandwidth, not
the lowest latency. generally, at least.
10 p.m.
On Mon, 18 Feb 2013 21:57:22 +0100, Paul Davis
<paul(a)linuxaudiosystems.com> wrote:
On Mon, Feb 18, 2013 at 3:36 PM,
<jonetsu(a)teksavvy.com> wrote:
From what I hear, the throughput of for example linux-lowlatency on Ubuntu
is 10% less than with linux-generic. So, that would be bad for servers in
deed.
Also, it is said to use more battery power, but I have not seen any data
on both of these things, so I really have no sources on that.
I do know that kernel developers in Ubuntu aren't interested in using
-lowlatency configs over -generic ones for these sort of reasons.
If a better response time from the kernel is
something that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ?
latency and bandwidth are opposing goals. server oriented (compute-based
or storage-based) systems want to have the highest possible bandwidth,
not
the lowest latency. generally, at least. 
11:59 p.m.
On Mon, February 18, 2013 12:36 pm, jonetsu(a)teksavvy.com wrote:
If a better response time from the kernel is something
that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ? Any drawbacks ? I presume the
Audio-oriented Linux distros do have lowlatency kernels by default, do
they ?
low latency does not equal performance.
low latency and high throughput are not the same either.
Low latency means servicing an audio device more often, complete with the
overhead involved in that. It means prioritizing one set of RT/lowlatency
processes over others for a set purpose. when running audio at a low
latency, the rest of my desktop slows down a lot to make sure my audio
does not glitch.
Low latency is a different set of priorities than performance.
--
Len Ovens
www.OvenWerks.net
19 Feb
19 Feb
12:43 a.m.
On Mon, 18 Feb 2013 23:59:30 +0100, Len Ovens <len(a)ovenwerks.net> wrote:
On Mon, February 18, 2013 12:36 pm,
jonetsu(a)teksavvy.com wrote:
Performance for _my_ averaged non-audio desktop usage isn't less good,
when using a kernel-rt or full preempt kernel with threadirqs set, than
when using a vanilla or so called desktop optimized kernel, so I'm usually
using a self compiled kernel-rt. However, I'm seldom toying around with my
computer, so "averaged non-audio" does mean that I use mail clients,
browsers and GIMP, even for consuming multimedia, I seldom use the
computer.
But making the kernel-rt a default, would be as bad, as making flashy
animated 3D desktops a default, so IMO distros should stop this desktop
insanity, but keep non-rt-kernels, while providing a kernel-rt by the
repositories.
2 Cents,
Ralf
If a better response time from the kernel is
something that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ? Any drawbacks ? I presume the
Audio-oriented Linux distros do have lowlatency kernels by default, do
they ?
low latency does not equal performance.
low latency and high throughput are not the same either.
Low latency means servicing an audio device more often, complete with the
overhead involved in that. It means prioritizing one set of RT/lowlatency
processes over others for a set purpose. when running audio at a low
latency, the rest of my desktop slows down a lot to make sure my audio
does not glitch.
Low latency is a different set of priorities than performance. 
2:55 a.m.
On 02/18/2013 01:42 PM, Ralf Mardorf wrote:
On Mon, 18 Feb 2013 23:59:30 +0100, Len Ovens
<len(a)ovenwerks.net> wrote:
I understand another argument against making an RT kernel the default
stock one is that a runaway RT process could produce an internal
denial-of-service condition. IIRC, the thought was that people who
actually needed an RT kernel knew about the risk and would accept it,
while ordinary people who don't need RT don't have to encounter it.
Vague recollection from something read somewhere, I think it was a
discussion list archive I found on the web somewhere.
--
David
gnome(a)hawaii.rr.com
authenticity, honesty, community
http://clanjones.org/david/
http://dancing-treefrog.deviantart.com/
On Mon, February 18, 2013 12:36 pm,
jonetsu(a)teksavvy.com wrote:
Performance for _my_ averaged non-audio desktop usage isn't less good,
when using a kernel-rt or full preempt kernel with threadirqs set, than
when using a vanilla or so called desktop optimized kernel, so I'm
usually using a self compiled kernel-rt. However, I'm seldom toying
around with my computer, so "averaged non-audio" does mean that I use
mail clients, browsers and GIMP, even for consuming multimedia, I seldom
use the computer.
But making the kernel-rt a default, would be as bad, as making flashy
animated 3D desktops a default, so IMO distros should stop this desktop
insanity, but keep non-rt-kernels, while providing a kernel-rt by the
repositories. If a better response time from the kernel is
something that's Good, why
isn't lowlatency kernels a default in Linux distros (well, at least in
Linux Mint and Fedora) If it is So Good, what are the arguments for not
having a lowlatency kernel by default ? Any drawbacks ? I presume the
Audio-oriented Linux distros do have lowlatency kernels by default, do
they ?
low latency does not equal performance.
low latency and high throughput are not the same either.
Low latency means servicing an audio device more often, complete with the
overhead involved in that. It means prioritizing one set of RT/lowlatency
processes over others for a set purpose. when running audio at a low
latency, the rest of my desktop slows down a lot to make sure my audio
does not glitch.
Low latency is a different set of priorities than performance. 
9:16 a.m.
On 19/02/13 04:36, jonetsu(a)teksavvy.com wrote:
If a better response time from the kernel is something
that's Good, why isn't
lowlatency kernels a default in Linux distros (well, at least in Linux Mint and
Fedora) If it is So Good, what are the arguments for not having a lowlatency
kernel by default ? Any drawbacks ? I presume the Audio-oriented Linux distros
do have lowlatency kernels by default, do they ?
aside from the other things mentioned there is a trade-off between GUI
responsiveness and audio latency ... if you do the full rt-audio set-up then the
programs you set as very high priority can easily lock everything else out. That
is fine if that is what you want, but it certainly isn't right for a default.
With less extreme settings there is still a cost re desktop interaction and that
is important for many people.
Simon
1:36 p.m.
On Tue, Feb 19, 2013 at 3:16 AM, Simon Wise <simonzwise(a)gmail.com> wrote:
On 19/02/13 04:36, jonetsu(a)teksavvy.com wrote:
on modern systems this is unlikely to be the case any more. (a) multicore
(b) kernel mechanisms to reserve a (small) fraction of available CPU for
non-RT tasks.
If a better response time from the kernel is
something that's Good, why
isn't
lowlatency kernels a default in Linux distros (well, at least in Linux
Mint and
Fedora) If it is So Good, what are the arguments for not having a
lowlatency
kernel by default ? Any drawbacks ? I presume the Audio-oriented Linux
distros
do have lowlatency kernels by default, do they ?
aside from the other things mentioned there is a trade-off between GUI
responsiveness and audio latency ... if you do the full rt-audio set-up
then the programs you set as very high priority can easily lock everything
else out. T
2:22 p.m.
On 19 February 2013 13:36, Paul Davis <paul(a)linuxaudiosystems.com> wrote:
On Tue, Feb 19, 2013 at 3:16 AM, Simon Wise
<simonzwise(a)gmail.com> wrote:
Indeed, I've had the same basic setup for a number of years, and this
month was the first time I noticed any slowdown in the rest of my
system while doing audio, and only now because I was working on a
session with a number of tracks and plugins far beyond most stuff I've
worked on before. The quadcore has been good to me for a long time.
Arve
aside from the other things mentioned there is a
trade-off between GUI
responsiveness and audio latency ... if you do the full rt-audio set-up then
the programs you set as very high priority can easily lock everything else
out. T
on modern systems this is unlikely to be the case any more. (a) multicore
(b) kernel mechanisms to reserve a (small) fraction of available CPU for
non-RT tasks.
4234
days inactive
4235
days old
linux-audio-user@lists.linuxaudio.org
10 comments
10 participants
participants (10)
-
Arve Barsnes -
Brett McCoy -
david -
Federico Bruni -
jonetsu＠teksavvy.com -
Kaj Ailomaa -
Len Ovens -
Paul Davis -
Ralf Mardorf -
Simon Wise