Question for linux gurus

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Profile dgnuff
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Message 14712 - Posted: 27 Apr 2006, 1:47:39 UTC
Last modified: 27 Apr 2006, 2:16:28 UTC

I suspect this may be a BOINC issue rather than a Rosetta issue, if so I'll take the question over to the Boinc forums.

However, is there a quick tweak I can do to one of the two linux systems I have crunching (Gentoo) that will allow it to use both halves of the CPU it's on. Exactly the same hardware (DELL 4700) as one of my XP systems, and my other linux box running Fedora Core. Both these two crunch two WU, while the Gentoo box only crunches one.

Linux boxen:

Gentoo
Fedora Core 4

Windows box:

Windows

Or will it even make a difference? I seem to remember a discussion on the Find-a-drug boards that mentioned running two WU on a hyperthreading intel box was actually counterproductive.

So what's the scoop here?

-- Edit -- added links to systems --
-- 2nd Edit -- found FC box doing the right thing --
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Message 14721 - Posted: 27 Apr 2006, 4:28:50 UTC - in response to Message 14712.  

I dont run gentoo but it sounds like your kernel is not SMP enabled.

Gentoo probably has a different kernel package which contains SMP support, so if you install that one and reboot you'll be able to use the 2nd.

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Profile River~~
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Message 14734 - Posted: 27 Apr 2006, 7:57:31 UTC - in response to Message 14721.  
Last modified: 27 Apr 2006, 8:19:50 UTC

I dont run gentoo but it sounds like your kernel is not SMP enabled.

Gentoo probably has a different kernel package which contains SMP support, so if you install that one and reboot you'll be able to use the 2nd.


First, if other people have this problem, check your BOINC general preferences (link from your personal a/c page). What is the max cpu setting? Even if your box has two cpus, and even if your operatijg system is up for them, BOINC will not run more than it is allowed.

Becasue the Win box runs OK, and because in the computer page it shows you as having only 1 cpu on the Gentoo box, I agree it is more likely to be about SMP

I had the same issue on DEbian and on a box that is currently running CPDN. Debian users can fix this by running aptitude, loading the pseudo-package called kernel, which suggests all the available pre-compiled options and you'd then pick the one with SMP in the name.

Gentoo has a more restricted range of pre-compiled kernels, which are really only intended to get you going. The Gentoo style is to re-compile your own kernel anyway, so their installer does less for you than (say) Debian's. The Gentoo creators figure there is no point spending their dev time creating a huge range of kernels that will only be used to support the user to roll their own.

If there is no pre-compiled kernel with SMP in its name, or if you have already custom compiled your kernel without SMP, then you need to look at your kernel compile-time options for the one to switch on SMP. Oh - and then recompile of course!

In my experience, with hands on tuning Gentoo gives the best results of any Linux distro, but without hends on tuning Gentoo often falls far short of the performance of say SuSe, Fedora, or Debian. In my mind Gentoo is strictly for people (like me) who get more fun out of tuning their system than out of using it ;-)

River~~

edits: added advice to other people, who may have similar symptoms but unlike dgnuff may simply have an issue with BOINC settings. Tip for replies: always consider that advice on these boards is acted on by others besides the original questionner. R~~
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Message 14750 - Posted: 27 Apr 2006, 13:53:32 UTC
Last modified: 27 Apr 2006, 13:54:46 UTC

You may want to look at Ubuntu. While the base install only supports single CPUs the package manager in there has the SMP kernel available for download and installation. The base install is a single ISO cd download unlike the big distros like Fedora or Suse. I run the AMD64 version my Dual cores and it performs well.

Ubuntu is super easy to setup and get running and seems to support a large range of platforms and hardware right out of the "box". They also have a live CD version so you can see if it suits your needs prior to a full blown install.
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Profile Dimitris Hatzopoulos

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Message 14795 - Posted: 27 Apr 2006, 21:35:08 UTC
Last modified: 27 Apr 2006, 21:40:57 UTC

Right, a Unix kernel needs to be SMP-enabled for a system to "recognize" the 2nd CPU (and any application, incl. BOINC to use it). I don't use Gentoo but found this:

Gentoo SMP kernel discussion

As others pointed out, in today's user-friendly systems, there's usually a "package" that installs the SMP-enabled kernel, e.g. for Debian (and Debian-derivative Ubuntu):


# apt-cache search smp
kernel-image-2.6.8-12-amd64-k8-smp - Linux kernel image for version 2.6.8 on AMD64 SMP systems
kernel-image-2.6.8-12-em64t-p4-smp - Linux kernel image for version 2.6.8 on Intel EM64T SMP systems
kernel-image-2.6.8-3-686-smp - Linux kernel image for version 2.6.8 on PPro/Celeron/PII/PIII/P4 SMP.


and you'd use something like

# apt-get install kernel-image-2.6.8-...


to install it, reboot and you're done.

But, if a CPU is HT (HyperThreaded) rather than "true" dual-core, then the performance diff is small and you might not want to bother with it (unless you like tweaking)
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Message 14810 - Posted: 28 Apr 2006, 1:23:07 UTC - in response to Message 14795.  

Right, a Unix kernel needs to be SMP-enabled for a system to "recognize" the 2nd CPU (and any application, incl. BOINC to use it). I don't use Gentoo but found this:

Gentoo SMP kernel discussion

As others pointed out, in today's user-friendly systems, there's usually a "package" that installs the SMP-enabled kernel, e.g. for Debian (and Debian-derivative Ubuntu):


Got it working, thanks to this link. Turns out I have a SMP enabled kernel running on the system already, but some comedian (i.e. the previous owner of the system) had disabled hyperthreading in the BIOS.

Turned on hyperthreading, and Gentoo is now crunching two at a time.

Thanks for all the help, guys!

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Message 14824 - Posted: 28 Apr 2006, 5:09:20 UTC - in response to Message 14810.  
Last modified: 28 Apr 2006, 5:14:02 UTC

Yep, Gentoo shows 2 cpu now so all of us can see the difference

(hey - that will confuse latecomers to this thread)


Thanks for all the help, guys!


you are very welcome - I've seen your posts elsewhere & you are not slow to offer help to others yourself

not to mention that avatar which makes me smile whenever you post ;-)
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Message boards : Number crunching : Question for linux gurus



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