SMP or default kenel?

rlculver · n00b Joined: 15 Aug 2003 Posts: 6

Hi,

I am just about to install Gentoo and was wondering which kernel to choose. I have a Pentium 4 2.8Ghz with HyperThreading enabled. Which one do I choose?

Thanks

Robert

nephros · Posted: Fri Aug 15, 2003 1:44 pm Post subject:

Choose the SMP kernel.

After it boots, do a cat /proc/cpuinfo.
If it shows two CPUs HyperThreading is working.
(You can also check dmesg. It sais wether it activates a "second" processor.)
You can then do all the configuration to take advantage of a SMP machine (like passing -j3 to make processes, see /etc/make.conf).

I am not sure which kernels support HT though.
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vbenares · Apprentice Joined: 13 Aug 2003 Posts: 205

nephros · Posted: Fri Aug 15, 2003 2:15 pm Post subject:

R0B_IX · Tux's lil' helper Joined: 15 Jun 2003 Posts: 83

Wow! Amazing info you just gave me there. I have been running gentoo for about 3 weeks on my 3.06ghz w/ HT laptop, and am still learning new things about it every day (as it should be

). Just a quick note, assuming you don't run into any problems, I would recomend smp-acpi when compiling your system. I found that it is almost manditory for my laptop because it doesn't appear to throttle correctly without it (and that leads to an overheating problem and then a suddent shutdown, which is never good

)
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Laptop:Sager 5670
CPU:3.06ghz w/HT enabled
RAM:512 megs PC2100
Video:ATI Radeon Mobility 9000
HD1:40 gig 5400 RPM 2.5" drive
HD2:20 gig 5400 RPM external 2.5" USB2 drive
OS of choice:Windows 3.1 (just kidding, it's gentoo)

szo · n00b Joined: 20 Jul 2003 Posts: 6

Actually, this would depend what kind of install you would perform. If it will be grp install, in which you presumably wont need internet, yes smp would be a nice choice.

However, upto now I never managed to run smp and network at the same time (hence got two kernel compiled, one when i have job more suitable for multiprocessing, one regular for internet, machine is 3.06 ht laptop)

So I believe in the end you better also have a "normal" kernel handy.

SZ

R0B_IX · Tux's lil' helper Joined: 15 Jun 2003 Posts: 83

Would you mind explaining what you mean by network. As of right now, I have always used smp with my laptop (also a 3.06ghz proc w/HT) and it seems as if I can get on the internet just fine. I have yet to try and share files from one computer to another, but would like to set that up next week. Are you saying that I am going to run into a road block if I try to do this with an smp kernel? Also, if you just mean geting on the internet never appears to work with smp, then you might have another problem with you setup, because I have done many stage 1 builds with the smp kernel without any problems. Thanks for any info you have on this topic.
_________________
Laptop:Sager 5670
CPU:3.06ghz w/HT enabled
RAM:512 megs PC2100
Video:ATI Radeon Mobility 9000
HD1:40 gig 5400 RPM 2.5" drive
HD2:20 gig 5400 RPM external 2.5" USB2 drive
OS of choice:Windows 3.1 (just kidding, it's gentoo)

zbert · n00b Joined: 01 Jul 2003 Posts: 37 Location: New York

I have a 3.06Ghz machine and when I try to boot of the LiveCD using "smp" everything just blanks out. Anybody know what I can try?
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--zbert

nahca · n00b Joined: 14 Aug 2003 Posts: 12

your 3.06ghz proc might not have HT

R0B_IX · Tux's lil' helper Joined: 15 Jun 2003 Posts: 83

does it attempt to load anything (i.e. do you see any scrolling commands/status updates)? or does it just instantly go blank?
_________________
Laptop:Sager 5670
CPU:3.06ghz w/HT enabled
RAM:512 megs PC2100
Video:ATI Radeon Mobility 9000
HD1:40 gig 5400 RPM 2.5" drive
HD2:20 gig 5400 RPM external 2.5" USB2 drive
OS of choice:Windows 3.1 (just kidding, it's gentoo)

Moled · l33t Joined: 09 Jul 2003 Posts: 635

the smp kernel doesn't have support for ht

theres an extra option you need and some kernel options to add at boottime to get it to work

zbert · n00b Joined: 01 Jul 2003 Posts: 37 Location: New York

szo · n00b Joined: 20 Jul 2003 Posts: 6

ROB_IX;

I meant internet, it just never activates saying some conflict. It may very well be a configuration problem, but I both used the same kernel as my regular with just activating smp (and taking out the apm as required) and it did not worked (and yes it finds 2 cpus). Also in live cd, gentoo kernel option works fine in terms of internet, but smp does not.

At this point, let me turn to zbert.

zbert;

can you please try smp-acpi kernel with passing noapic option, if i am not mistaken (press F2 and look for the one that says disable this if you are experiencing hardware problems). This seems to work for me, and all other generate panic in my live cd smp kernel.

i.e at boot you write stg like "smp noapic" or "smp-acpi noapic"

Then ckeck the lines whether it finds cpu0 and cpu1 or only cpu0, while information is flowing down or by investigating output of "dmesg".

Care,
SZ

lotusvale · Guru Joined: 06 Mar 2003 Posts: 339 Location: Canada

is that the main thing SMP will do for you? for HT-enabled?
can anyone tell me what other advantages of it? since i thought this was for "Symmetic Multi Processing", which handles more than one cpu in the same mobo.
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zbert · n00b Joined: 01 Jul 2003 Posts: 37 Location: New York

id10t · Tux's lil' helper Joined: 18 May 2002 Posts: 100

Hyperthreading is a smp implementation in a single cpu.

Anyway, I've been running a SMP system for a long time now, and to be honest, I'll never go back to a single processor system by choice. The dual P2-450s I just replaced "felt" faster than the single 2.4 celeron I have on my desk at work, both with Slack 8.1/9.0.
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Paradigmbreak · n00b Joined: 02 Sep 2003 Posts: 64

zbert- For what it is worth, i had the same problem with a dual athlon mp and I used "smb-nofb noapic" and it worked. Would run fine with fb if i tried a single processor install with no options (just hitting return). So you might try that. If that fails perhaps some voodoo charms might do the trick.

zbert · n00b Joined: 01 Jul 2003 Posts: 37 Location: New York

Thanks Paradigmbreak. I've decided to move on for the time being and wait for the next kernel which may have better support for hyperthreading.
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--zbert