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Old 11-07-2009, 10:51 PM
Stroller
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

On 7 Nov 2009, at 11:32, Volker Armin Hemmann wrote:

...
I'd love to know what the name of the kernel module is so I can
unload

it:

$ zcat /proc/config.gz | grep -i pegasus
CONFIG_USB_PEGASUS=y


it is not a module, but compiled in. You have to rebuild your
kernel. And

probably decrapify your config a lot.


Doh! I was fairly tired when I wrote that, sorry.

I tend to just occasionally copy the kernel .config from that used on
the latest Knoppix disk, and `make oldconfig` between times. I figure
I don't know enough about the kernel that I'm likely to be able to
select a better set of options than that, and learning what to change
will surely not produce improvements worth the time expended.


I would love a recommended "default" kernel .config - either for
Gentoo or Linux in general, but based towards on "small server" use -
but I'm not aware of anyone publishing one. I like the notion of a
small, minimal and "sleek" kernel, but with lots of modules available
to load as necessary, should I install a new PCI card. If anyone has
any low-overhead suggestions, I would love to hear them.


Stroller.
 
Old 11-07-2009, 11:10 PM
Volker Armin Hemmann
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

On Sonntag 08 November 2009, Stroller wrote:
> On 7 Nov 2009, at 11:32, Volker Armin Hemmann wrote:
> >> ...
> >> I'd love to know what the name of the kernel module is so I can
> >> unload
> >> it:
> >>
> >> $ zcat /proc/config.gz | grep -i pegasus
> >> CONFIG_USB_PEGASUS=y
> >
> > it is not a module, but compiled in. You have to rebuild your
> > kernel. And
> > probably decrapify your config a lot.
>
> Doh! I was fairly tired when I wrote that, sorry.
>
> I tend to just occasionally copy the kernel .config from that used on
> the latest Knoppix disk, and `make oldconfig` between times. I figure
> I don't know enough about the kernel that I'm likely to be able to
> select a better set of options than that, and learning what to change
> will surely not produce improvements worth the time expended.
>
> I would love a recommended "default" kernel .config - either for
> Gentoo or Linux in general, but based towards on "small server" use -
> but I'm not aware of anyone publishing one. I like the notion of a
> small, minimal and "sleek" kernel, but with lots of modules available
> to load as necessary, should I install a new PCI card. If anyone has
> any low-overhead suggestions, I would love to hear them.
>
> Stroller.
>

using a livecds kernel is probably the worst decision out there.

http://www.kroah.com/lkn/

as you can see, you don't have to download it.

Or just do it step for step, reading help files.

seccomp? Except Andrea Arcangeli nobody uses it. Can be deactivated. I2O?
Almost nobody uses it. Especially not 'commodity' hardware, out it goes. Numa?
Do you have a multi-socket system? No? Then you don't need it. ... you can
remove a lot of cruft that way. Namespaces - you don't need it? Kick 'em out.
Group scheduling? Sure, a great way to reduce performance...

...
 
Old 11-07-2009, 11:24 PM
Stroller
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

On 8 Nov 2009, at 00:10, Volker Armin Hemmann wrote:

...
using a livecds kernel is probably the worst decision out there.

http://www.kroah.com/lkn/

as you can see, you don't have to download it.

Or just do it step for step, reading help files.

seccomp? Except Andrea Arcangeli nobody uses it. Can be deactivated.
I2O?
Almost nobody uses it. Especially not 'commodity' hardware, out it
goes. Numa?
Do you have a multi-socket system? No? Then you don't need it. ...
you can
remove a lot of cruft that way. Namespaces - you don't need it? Kick
'em out.

Group scheduling? Sure, a great way to reduce performance...




But Volker, if it takes me an hour to decrapify my kernel config and
make it faster, it will probably take 1000 years for those speed
improvements to pay off.


If I had unlimited time then I would love to read that book. I really
LIKE the idea of decrapifying my kernel config. But realistically, any
time I spend on it is time wasted, for which no difference will be
appreciable.


Stroller.
 
Old 11-07-2009, 11:50 PM
Volker Armin Hemmann
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

On Sonntag 08 November 2009, Stroller wrote:
> On 8 Nov 2009, at 00:10, Volker Armin Hemmann wrote:
> > ...
> > using a livecds kernel is probably the worst decision out there.
> >
> > http://www.kroah.com/lkn/
> >
> > as you can see, you don't have to download it.
> >
> > Or just do it step for step, reading help files.
> >
> > seccomp? Except Andrea Arcangeli nobody uses it. Can be deactivated.
> > I2O?
> > Almost nobody uses it. Especially not 'commodity' hardware, out it
> > goes. Numa?
> > Do you have a multi-socket system? No? Then you don't need it. ...
> > you can
> > remove a lot of cruft that way. Namespaces - you don't need it? Kick
> > 'em out.
> > Group scheduling? Sure, a great way to reduce performance...
>
> But Volker, if it takes me an hour to decrapify my kernel config and
> make it faster, it will probably take 1000 years for those speed
> improvements to pay off.
>
> If I had unlimited time then I would love to read that book. I really
> LIKE the idea of decrapifying my kernel config. But realistically, any
> time I spend on it is time wasted, for which no difference will be
> appreciable.
>
> Stroller.
>

I am not you, but I need maybe 5min for a config

and there are more benefits. Smaller binary, more cpu cache free for real data.
Better performance lies that way. Also, you don't have to wonder about
processes you did not start. Security is also a point. A smaller codebase in
use is a saver codebase in use. A lot of bugs only affect kernels with certain
features turned on - it is very relaxing if you don't have that feature...
 
Old 11-08-2009, 05:55 AM
Dale
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

Volker Armin Hemmann wrote:
> On Sonntag 08 November 2009, Stroller wrote:
>
>> On 8 Nov 2009, at 00:10, Volker Armin Hemmann wrote:
>>
>>> ...
>>> using a livecds kernel is probably the worst decision out there.
>>>
>>> http://www.kroah.com/lkn/
>>>
>>> as you can see, you don't have to download it.
>>>
>>> Or just do it step for step, reading help files.
>>>
>>> seccomp? Except Andrea Arcangeli nobody uses it. Can be deactivated.
>>> I2O?
>>> Almost nobody uses it. Especially not 'commodity' hardware, out it
>>> goes. Numa?
>>> Do you have a multi-socket system? No? Then you don't need it. ...
>>> you can
>>> remove a lot of cruft that way. Namespaces - you don't need it? Kick
>>> 'em out.
>>> Group scheduling? Sure, a great way to reduce performance...
>>>
>> But Volker, if it takes me an hour to decrapify my kernel config and
>> make it faster, it will probably take 1000 years for those speed
>> improvements to pay off.
>>
>> If I had unlimited time then I would love to read that book. I really
>> LIKE the idea of decrapifying my kernel config. But realistically, any
>> time I spend on it is time wasted, for which no difference will be
>> appreciable.
>>
>> Stroller.
>>
>>
>
> I am not you, but I need maybe 5min for a config
>
> and there are more benefits. Smaller binary, more cpu cache free for real data.
> Better performance lies that way. Also, you don't have to wonder about
> processes you did not start. Security is also a point. A smaller codebase in
> use is a saver codebase in use. A lot of bugs only affect kernels with certain
> features turned on - it is very relaxing if you don't have that feature...
>
>

I agree. When I first installed Gentoo I had never built a kernel or
even run make menuconfig. It took me three tries to get a bootable
kernel but it was worth it. I don't put something in my kernel that
isn't needed or that I use, well except for NTFS support. I may have to
rescue my brother one day. Point being, you only have to build one good
kernel then you can copy and run make oldconfig after that. I'm with
Volker on this, 5 minutes at most once you get a good build. If you
know your system really well, you may can start from scratch and config
one in that time.

You really need to learn to make your own kernel. After all, it's the
first file your computer loads when the OS starts booting up. It's also
the first level of security. It is what deals with all the hardware on
the most basic level.

You also get to see your head swell when you get a lean kernel and say
"I did that".

Dale

:-) :-)
 
Old 11-08-2009, 09:10 AM
Florian Philipp
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

Volker Armin Hemmann schrieb:
> On Sonntag 08 November 2009, Stroller wrote:
>> On 7 Nov 2009, at 11:32, Volker Armin Hemmann wrote:
>>>> ...
>>>> I'd love to know what the name of the kernel module is so I can
>>>> unload
>>>> it:
>>>>
>>>> $ zcat /proc/config.gz | grep -i pegasus
>>>> CONFIG_USB_PEGASUS=y
>>> it is not a module, but compiled in. You have to rebuild your
>>> kernel. And
>>> probably decrapify your config a lot.
>> Doh! I was fairly tired when I wrote that, sorry.
>>
>> I tend to just occasionally copy the kernel .config from that used on
>> the latest Knoppix disk, and `make oldconfig` between times. I figure
>> I don't know enough about the kernel that I'm likely to be able to
>> select a better set of options than that, and learning what to change
>> will surely not produce improvements worth the time expended.
>>
>> I would love a recommended "default" kernel .config - either for
>> Gentoo or Linux in general, but based towards on "small server" use -
>> but I'm not aware of anyone publishing one. I like the notion of a
>> small, minimal and "sleek" kernel, but with lots of modules available
>> to load as necessary, should I install a new PCI card. If anyone has
>> any low-overhead suggestions, I would love to hear them.
>>
>> Stroller.
>>
>
> using a livecds kernel is probably the worst decision out there.
>
> http://www.kroah.com/lkn/
>
> as you can see, you don't have to download it.
>
[...]

You could also simply emerge it: app-doc/linux-kernel-in-a-nutshell
 
Old 11-08-2009, 09:24 AM
Dale
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

Florian Philipp wrote:
> Volker Armin Hemmann schrieb:
>
>> On Sonntag 08 November 2009, Stroller wrote:
>>
>>> On 7 Nov 2009, at 11:32, Volker Armin Hemmann wrote:
>>>
>>>>> ...
>>>>> I'd love to know what the name of the kernel module is so I can
>>>>> unload
>>>>> it:
>>>>>
>>>>> $ zcat /proc/config.gz | grep -i pegasus
>>>>> CONFIG_USB_PEGASUS=y
>>>>>
>>>> it is not a module, but compiled in. You have to rebuild your
>>>> kernel. And
>>>> probably decrapify your config a lot.
>>>>
>>> Doh! I was fairly tired when I wrote that, sorry.
>>>
>>> I tend to just occasionally copy the kernel .config from that used on
>>> the latest Knoppix disk, and `make oldconfig` between times. I figure
>>> I don't know enough about the kernel that I'm likely to be able to
>>> select a better set of options than that, and learning what to change
>>> will surely not produce improvements worth the time expended.
>>>
>>> I would love a recommended "default" kernel .config - either for
>>> Gentoo or Linux in general, but based towards on "small server" use -
>>> but I'm not aware of anyone publishing one. I like the notion of a
>>> small, minimal and "sleek" kernel, but with lots of modules available
>>> to load as necessary, should I install a new PCI card. If anyone has
>>> any low-overhead suggestions, I would love to hear them.
>>>
>>> Stroller.
>>>
>>>
>> using a livecds kernel is probably the worst decision out there.
>>
>> http://www.kroah.com/lkn/
>>
>> as you can see, you don't have to download it.
>>
>>
> [...]
>
> You could also simply emerge it: app-doc/linux-kernel-in-a-nutshell
>
>

If he goes to that link provided earlier, he can scroll down and
download the pdf files. I found this to be the best page since it talks
about building a kernel in pretty good detail.

Chapter 4: Configuring and Building

It even has pictures to help give a clearer picture and even shows
different ways of doing the same thing. It even shows how to do this in
a GUI.

Do we really not have to do make modules_install any more?

Dale

:-) :-)
 
Old 11-08-2009, 08:20 PM
Stroller
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

On 8 Nov 2009, at 06:55, Dale wrote:

...
I am not you, but I need maybe 5min for a config

and there are more benefits. Smaller binary, more cpu cache free
for real data.
Better performance lies that way. Also, you don't have to wonder
about
processes you did not start. Security is also a point. A smaller
codebase in
use is a saver codebase in use. A lot of bugs only affect kernels
with certain
features turned on - it is very relaxing if you don't have that
feature...


I agree. When I first installed Gentoo I had never built a kernel or
even run make menuconfig. It took me three tries to get a bootable
kernel but it was worth it. I don't put something in my kernel that
isn't needed or that I use, well except for NTFS support. I may
have to
rescue my brother one day. Point being, you only have to build one
good

kernel then you can copy and run make oldconfig after that. I'm with
Volker on this, 5 minutes at most once you get a good build. If you
know your system really well, you may can start from scratch and
config

one in that time.

You really need to learn to make your own kernel. ...


Whilst I agree in principle that a good (slim?) kernel is better and
your comments on that, I am sceptical whether the majority of people
have the knowledge to make any significant performance or security
improvements.


AIUI the kernels shipped by distros like Red Hat, for instance, are
configured by the very people that work on and maintain the mainline
kernel tree. How can any of us simple end-users compete with that?


I imagine it to be very easy for any of us normal people to enable or
disable options that make significant performance impact - but we
would never know it, because we're not benchtesting it or even
qualified to assess proper benchtests.


I cannot believe that in a day you could study this subject
sufficiently to have any reasonable competence on the matter. And thus
if you do spend only a day, that's wasted time. I would add that the
kernel is evolving constantly, and in a year's time your knowledge -
and your .config - is likely to be at least somewhat outdated.


I chose to copy the .config from Knoppix because it's easy to get hold
of that, but also because it's selected by someone who knows more than
me, and it is likely to work with any hardware I install into my
machine or connect by USB. I take Volker's point that a LiveCD .config
_could_ be the worst possible choice so I'm open to alternatives, but
I hope those who say I should "learn to make your own kernel"
appreciate my points over how effectual that will be - sure, I can
delete my .config and start again with `make menuconfig` and I can go
through every option and read the help, and I'm sure I'll get just as
good results as 80% of the people on this list, but I just don't know
that that's much of an answer.


Stroller.
 
Old 11-08-2009, 08:35 PM
Alan McKinnon
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

On Sunday 08 November 2009 23:20:31 Stroller wrote:
> > You really need to learn to make your own kernel. ...
>
> Whilst I agree in principle that a good (slim?) kernel is better and
> your comments on that, I am sceptical whether the majority of people
> have the knowledge to make any significant performance or security
> improvements.
>
> AIUI the kernels shipped by distros like Red Hat, for instance, are
> configured by the very people that work on and maintain the mainline
> kernel tree. How can any of us simple end-users compete with that?
>
> I imagine it to be very easy for any of us normal people to enable or
> disable options that make significant performance impact - but we
> would never know it, because we're not benchtesting it or even
> qualified to assess proper benchtests.
>
> I cannot believe that in a day you could study this subject
> sufficiently to have any reasonable competence on the matter. And thus
> if you do spend only a day, that's wasted time. I would add that the
> kernel is evolving constantly, and in a year's time your knowledge -
> and your .config - is likely to be at least somewhat outdated.
>
> I chose to copy the .config from Knoppix because it's easy to get hold
> of that, but also because it's selected by someone who knows more than
> me, and it is likely to work with any hardware I install into my
> machine or connect by USB. I take Volker's point that a LiveCD .config
> could be the worst possible choice so I'm open to alternatives, but
> I hope those who say I should "learn to make your own kernel"
> appreciate my points over how effectual that will be - sure, I can
> delete my .config and start again with `make menuconfig` and I can go
> through every option and read the help, and I'm sure I'll get just as
> good results as 80% of the people on this list, but I just don't know
> that that's much of an answer.

You are reading way more into the subject than is actually there.

Red Hat employees do work on mainline and do write kernel code. But finding a
bug, writing new code and fixing security exploits are very different
activities to simply configuring the code that is there. And that is what RH
do - they take the code that is already there, apply whatever backport and
experimental patches suits their distro, then go through menuconfig switching
some things on and some things off. Their needs are different to yours - they
need their kernel to run on just about any hardware on the planet, so they
build a horrendously complex initrd with support for every known boot device,
then build every module that even half-way works. And also enable every known
kernel sub-system (because someone somewhere is going to use it).

By your analogy, you might consider Red Hat more qualified than you to decide
if you should build an MTA with or without LDAP support. Which is of course
patently ridiculous - if you know you need LDAP then you need it. Otherwise
you don't (and this is not a security issue, it's a features issue)

If you configure your own kernel, you only need build the bits you use. The
sole benefit for a Gentoo users to using a custom distro kernel is support for
things not in mainline (like some entire FibreChannel product ranges out
there). But please note that even if you copy an RH .config, you do not have
those patches to hand so you will not get those extra features. Unless you
patched the ebuild yourself, in which case you are already au-fait with
building a kernel and we would not be having this discussion.

In summary, I hear your reasoning and understand your concerns. But it is
flawed and you are worried about something that is not actually there.


--
alan dot mckinnon at gmail dot com
 
Old 11-08-2009, 09:20 PM
Dale
 
Default decrapify your kernel config WAS: ps shows pegasus process running - what is it?

Alan McKinnon wrote:
> On Sunday 08 November 2009 23:20:31 Stroller wrote:
>
>>> You really need to learn to make your own kernel. ...
>>>
>> Whilst I agree in principle that a good (slim?) kernel is better and
>> your comments on that, I am sceptical whether the majority of people
>> have the knowledge to make any significant performance or security
>> improvements.
>>
>> AIUI the kernels shipped by distros like Red Hat, for instance, are
>> configured by the very people that work on and maintain the mainline
>> kernel tree. How can any of us simple end-users compete with that?
>>
>> I imagine it to be very easy for any of us normal people to enable or
>> disable options that make significant performance impact - but we
>> would never know it, because we're not benchtesting it or even
>> qualified to assess proper benchtests.
>>
>> I cannot believe that in a day you could study this subject
>> sufficiently to have any reasonable competence on the matter. And thus
>> if you do spend only a day, that's wasted time. I would add that the
>> kernel is evolving constantly, and in a year's time your knowledge -
>> and your .config - is likely to be at least somewhat outdated.
>>
>> I chose to copy the .config from Knoppix because it's easy to get hold
>> of that, but also because it's selected by someone who knows more than
>> me, and it is likely to work with any hardware I install into my
>> machine or connect by USB. I take Volker's point that a LiveCD .config
>> could be the worst possible choice so I'm open to alternatives, but
>> I hope those who say I should "learn to make your own kernel"
>> appreciate my points over how effectual that will be - sure, I can
>> delete my .config and start again with `make menuconfig` and I can go
>> through every option and read the help, and I'm sure I'll get just as
>> good results as 80% of the people on this list, but I just don't know
>> that that's much of an answer.
>>
>
> You are reading way more into the subject than is actually there.
>
> Red Hat employees do work on mainline and do write kernel code. But finding a
> bug, writing new code and fixing security exploits are very different
> activities to simply configuring the code that is there. And that is what RH
> do - they take the code that is already there, apply whatever backport and
> experimental patches suits their distro, then go through menuconfig switching
> some things on and some things off. Their needs are different to yours - they
> need their kernel to run on just about any hardware on the planet, so they
> build a horrendously complex initrd with support for every known boot device,
> then build every module that even half-way works. And also enable every known
> kernel sub-system (because someone somewhere is going to use it).
>
> By your analogy, you might consider Red Hat more qualified than you to decide
> if you should build an MTA with or without LDAP support. Which is of course
> patently ridiculous - if you know you need LDAP then you need it. Otherwise
> you don't (and this is not a security issue, it's a features issue)
>
> If you configure your own kernel, you only need build the bits you use. The
> sole benefit for a Gentoo users to using a custom distro kernel is support for
> things not in mainline (like some entire FibreChannel product ranges out
> there). But please note that even if you copy an RH .config, you do not have
> those patches to hand so you will not get those extra features. Unless you
> patched the ebuild yourself, in which case you are already au-fait with
> building a kernel and we would not be having this discussion.
>
> In summary, I hear your reasoning and understand your concerns. But it is
> flawed and you are worried about something that is not actually there.
>
>

What he said plus this little tidbit of info. When I built my first
kernel, I had no howto except for the basic instructions in the Gentoo
install guide. This was about 6 years or so ago and there was not a lot
on configuring a kernel except for the options Gentoo needed. It took
me three tries to get one to boot and work pretty well and all of a hour
at most. A lot of that hour was compiling the kernel.

You seem to think it takes a rocket scientist to build a kernel, it
doesn't. You just have to know what hardware you have and then enable
the features you need. Once you get a good one built, using make
oldconfig works really well. You can config a kernel in less than five
minutes most likely then compile and you are done. If you update fairly
regular, make oldconfig will work fine and not cause you the trouble you
had in the beginning.

Dale

:-) :-)
 

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