Subject: [alpine-devel] Limited number of CPUs

From: Florian Heigl <[email-masked]>
Date: Tue, 15 Nov 2011 18:23:34 +0100

Hi,

I have a question about the maximum number of CPUs in a default Alpine kernel.
I had noticed this on 2.2.2 and now on 2.3.1, too.

In a dual-12core Opteron box I see only 8 active CPUs.

localhost:~# grep proc /proc/cpuinfo
processor	: 0
processor	: 1
processor	: 2
processor	: 3
processor	: 4
processor	: 5
processor	: 6
processor	: 7

I guess this limit was set somewhere and never good into anybodys way,
but now that
Alpine is starting to have Xen dom0 support this (might) be an issue for some.

Ideally you only hand over 2-3 CPU cores (as much as you need for
network and disk IO)
to the Xen management VM dom0 and the rest is just for "payload"
virtual machines.

But not everyone does it like that so it would be nice to have all available.

Does anyone know if this is an intentional limit?

Greetings,
Florian

-- 
the purpose of libvirt is to provide an abstraction layer hiding all
xen features added since 2006 until they were finally understood and
copied by the kvm devs.

---
Unsubscribe:  [email-masked]
Help:         [email-masked]
---

---

From: William Pitcock <[email-masked]>
Date: Wed, 16 Nov 2011 03:47:47 -0600

Hi,

On Tue, 15 Nov 2011 18:23:34 +0100
Florian Heigl <[email-masked]> wrote:

> Hi,
> 
> I have a question about the maximum number of CPUs in a default
> Alpine kernel. I had noticed this on 2.2.2 and now on 2.3.1, too.
> 

This was a regression introduced at some point (not entirely sure when).
It has been fixed by 'linux-grsec=3.0.9-r1@edge'.

If your APK does not recognize edge repo, you can add it to
your /etc/apk/repositors like so:

"@edge http://nl.alpinelinux.org/alpine/edge/main"

I assume that Natanael will probably backport the change to 2.3 soonish.

William

---

---

From: Florian Heigl <[email-masked]>
Date: Wed, 16 Nov 2011 12:17:23 +0100

Hi,

> It has been fixed by 'linux-grsec=3.0.9-r1@edge'.

thanks for the reply.
I had upgraded to edge for installing Xen and only seen 8 CPUs even after that.
I'll check my kernel version.

That aside: Alpine now generates a working bootloader config for Xen.
Some other things are still open, but compared to what I tested during
the last weeks (Ubuntu, OpenSUSE), half-finished Alpine Xen support
comes out best ;)

Greetings,
flo

---

---

From: Natanael Copa <[email-masked]>
Date: Wed, 16 Nov 2011 13:26:16 +0100

On Wed, 16 Nov 2011 12:17:23 +0100
Florian Heigl <[email-masked]> wrote:

> > This was a regression introduced at some point (not entirely sure
> > when). It has been fixed by 'linux-grsec=3.0.9-r1@edge'.
> 
> thanks for the reply.
> I had upgraded to edge for installing Xen and only seen 8 CPUs even
> after that. I'll check my kernel version.

what does uname -a say?

> the last weeks (Ubuntu, OpenSUSE), half-finished Alpine Xen support

nice!

-nc

---

---

From: Florian Heigl <[email-masked]>
Date: Wed, 16 Nov 2011 22:41:30 +0100

Hi there,

I looked at the system again now.

> what does uname -a say?

waxh0015:~# uname -a
Linux waxh0015 3.0.9-grsec #2-Alpine SMP Wed Nov 16 09:37:45 UTC 2011
x86_64 GNU/Linux
waxh0015:~# grep -c proc /proc/cpuinfo
24

so this is fixed, as you expected. fixed before I even found it :)

There was a problem with my upgrade to edge this time. You have to
know I'm magnetic to errors and if I do something the same working way
twice, I'll just have to do it using a different, non-working way on
the third time.

The wiki tells us:
"Add the edge repository to /etc/apk/repositories:
echo http://dl-3.alpinelinux.org/alpine/edge/main >> /etc/apk/repositories
or just edit the file in-place (replace v2.2 with your release)
sed -i -e 's/v2.2/edge/g' /etc/apk/repositories"

Adding edge to the file cannot work i think. One has to replace one's
"main" 2.x source with edge.
(This is what I hit yesterday, I had really wanted something to copy
and paste since it was late)

I would edit the page if i were sure :)

Greetings,
Florian

---

---

From: Natanael Copa <[email-masked]>
Date: Fri, 18 Nov 2011 08:22:33 +0100

On Wed, 16 Nov 2011 22:41:30 +0100

> Hi there,

hi!
 
> echo http://dl-3.alpinelinux.org/alpine/edge/main
> >> /etc/apk/repositories or just edit the file in-place (replace v2.2
> >> with your release)

Um... I think it was supposed to work. apk-tools have got a new
dependency resolver so it might be something there.

I tried in a virtual machine and I was not able to reproduce.

---

---

From: Florian Heigl <[email-masked]>
Date: Fri, 18 Nov 2011 08:30:05 +0100

Hi,

> I tried in a virtual machine and I was not able to reproduce.

Oki, nevermind then.
If I see it again I'll bring along more debug info.

Thanks for the answer :)

---