Kernel Troubles

[kidzer]

So, I'm now a (wannabe!) Gentoo User, and I'm working on building my own Kernel at the mo, I've got most of it sorted, but my main issue at the moment is that of CPU cores.

I've created a kernel using Genkernel which I'm keeping as a backup incase I mess up every other kernel image I have, but I'm obviously after a more streamlined one, as the Genkernel one takes ages to boot!

So, I've got it mostly sorted, but when I run htop all I see is 1 CPU instead of two seperate CPU graphs for each core in my CPU, if I run htop on my genkernel Kernel, I see two. I have the required options enabled as modules in my Kernel for having multi-core support (SMT (or SMP, possibly) Support is the option I'm after I think) - and yet I still just see one core. One thing I did notice however, when I looked in the help section for that SMT/SMP option is that it says I should also enable 'Enhanced Real Time Clock' - again, that name is from memory - I'm Kernel building at the mo so I can't check (I don't think), but I can't find that option anywhere - I even had a look in my .config file for any mentions of RTC, but didn't see an 'Enhanced' one anywhere.

...any ideas folks?

Cheers!

...awesome, after I get this going, I've got to learn Portage, and also - why does OpenSSH-Server have LDAP as a dependency, grr!

[aidanjt]

So, I'm now a (wannabe!) Gentoo User, and I'm working on building my own Kernel at the mo, I've got most of it sorted, but my main issue at the moment is that of CPU cores.

So, you'll be needing a Gentoo user then...

*looks around*

Nobody?..

I've created a kernel using Genkernel which I'm keeping as a backup incase I mess up every other kernel image I have, but I'm obviously after a more streamlined one, as the Genkernel one takes ages to boot!

So, I've got it mostly sorted, but when I run htop all I see is 1 CPU instead of two seperate CPU graphs for each core in my CPU, if I run htop on my genkernel Kernel, I see two. I have the required options enabled as modules in my Kernel for having multi-core support (SMT (or SMP, possibly) Support is the option I'm after I think) - and yet I still just see one core. One thing I did notice however, when I looked in the help section for that SMT/SMP option is that it says I should also enable 'Enhanced Real Time Clock' - again, that name is from memory - I'm Kernel building at the mo so I can't check (I don't think), but I can't find that option anywhere - I even had a look in my .config file for any mentions of RTC, but didn't see an 'Enhanced' one anywhere.

First make sure your CPU cores are detected by the kernel, cat /proc/cpuinfo will enumerate every CPU the kernel detects, just in case htop is being funny. Assuming you really are one CPU short of a happy meal, then make sure the following kernel options are 'y':
CONFIG_SMP=y
CONFIG_SCHED_MC=y

If you have a Hyperthreading/Symetrical Multithreading type CPU (P4 Prescott/Pentium D/i7/etc), have CONFIG_SCHED_SMT=y was well, poke around Processor type and Features in menuconfig anyway, see if anything jumps out. Also pay attention to the Processor Family option. Handy that.

...awesome, after I get this going, I've got to learn Portage, and also - why does OpenSSH-Server have LDAP as a dependency, grr!

Disable the ldap useflag, it's set in make.profile. *edit* I should probably expand on this, edit /etc/make.conf and set USE="-ldap"

If you're still stuck, pastebin the output of emerge --info and .config.

[12GaugeShotty]

So, I'm now a (wannabe!) Gentoo Use...

Have you thought about trying here for any support?

http://forums.gentoo.org

[kidzer]

@12GaugeShotty - yeah, I'm registered over there, but I've not posted yet - I had a search for similar issues but thought I'd post here first in the hope that aidanjt would see it and reply - I understand he has some experience with this particular brand of Penguin-based OS, turns out that plan worked!

@aidanjt I had a look in my .config for those Kernel options, the last one you mentioned wasn't enabled, so I enabled it and built the kernel again, but still no luck.

I'll pastebin that info at some point today, probably when I'm home from work, and I'll shove the link here.

Cheers!

Edit: /proc/cpuinfo confirms just the one core, I'll shove that up too.

[aidanjt]

kidzer: ah, and do me a big big big favour and grep out lines starting with # in your .config before pastebinning. `grep -v "#" .config`will do it. Cheers.

[kidzer]

Right, here's my .config and the resulf of emerge --info:

- http://pastebin.com/m1b0dc478
- http://pastebin.com/m2f0a9271

Cheers!

[kidzer]

I may have a solution:

voyager ~ # cat /usr/src/linux/.config | grep ACPI
# Power management and ACPI options
# CONFIG_ACPI is not set

I read online ACPI is required for decent SMT support, otherwise the Kernel uses some unreliable old method of detecting CPUs/Cores, I've just enabled it and I'm compiling again, I'll test it tonight once I've finished emerging gnome - 219 packages to go, 62 to go!

[aidanjt]

Yup, bingo. You'll be needing that alright. This is an AMD machine too right?.. Make sure ACPI Processor support is 'y', and, go into CPU Frequency Scaling and set 'y' to AMD Operon/Athlon64 PowerNow to save the planet while you're not burning a hole in the o-zone layer (emerging ), and set the default governor to ondemand. You'll definitely want to use the Deadline (more server/database tasks) or CFQ (Desktop) I/O schedulers, Anticipatory is awfully inefficient.

Sorry about the delay, I was running around town.

[kidzer]

No worries, its an Intel CPU on board this machine - but I've got some Intel-specific stuff enabled already.

I'll fiddle about with all that once I've got both cores working on the Ozone Layer!

[aidanjt]

Yeah the Intel chips uses ACPI CPUFreq, so 'y' that instead.