Gentoo Forums
Gentoo Forums
Gentoo Forums
Quick Search: in
SMT (Hyperthreading) and/or Multi-core scheduler support
View unanswered posts
View posts from last 24 hours

 
Reply to topic    Gentoo Forums Forum Index Kernel & Hardware
View previous topic :: View next topic  
Author Message
Cr0t
l33t
l33t


Joined: 27 Apr 2002
Posts: 944
Location: USA

PostPosted: Fri May 03, 2013 6:16 pm    Post subject: SMT (Hyperthreading) and/or Multi-core scheduler support Reply with quote

The kernel has an option for "SMT (Hyperthreading) scheduler support" and "Multi-core scheduler support". If you have a system with HT and physical cpus, do you select both?

I have been just selecting multi-core scheduler and all the cpus are being used and show up for that matter.

Any reason why SMT is still listed since multi-core finds the HT cpus as well?
_________________
cya
    ©®0t
Back to top
View user's profile Send private message
Gusar
Advocate
Advocate


Joined: 09 Apr 2005
Posts: 2665
Location: Slovenia

PostPosted: Fri May 03, 2013 8:49 pm    Post subject: Reply with quote

You should use SMT. Yeah, multi-core will work too, sorta, but the kernel will think all cores are equal. The cores are not equal with hyperthreading though, and SMT will make the kernel aware of that.

If you select both, the kernel will use SMT if it sees the machine has hyperthreading, and multi-core otherwise. It will not use both.
Back to top
View user's profile Send private message
_______0
Guru
Guru


Joined: 15 Oct 2012
Posts: 521

PostPosted: Sat May 04, 2013 12:35 pm    Post subject: wrong answer! Reply with quote

the answer is in the help tab. Hyperthreading is, exclusively, for pentium4s, the other for the rest.
Back to top
View user's profile Send private message
Gusar
Advocate
Advocate


Joined: 09 Apr 2005
Posts: 2665
Location: Slovenia

PostPosted: Sat May 04, 2013 1:15 pm    Post subject: Re: wrong answer! Reply with quote

_______0 wrote:
the answer is in the help tab. Hyperthreading is, exclusively, for pentium4s, the other for the rest.

Incorrect. Pentium 4 was the first processor that had hyperthreading, but Core i3/5/7 processors have it too.
Back to top
View user's profile Send private message
nlsa8z6zoz7lyih3ap
Guru
Guru


Joined: 25 Sep 2007
Posts: 388
Location: Canada

PostPosted: Sat May 04, 2013 3:08 pm    Post subject: Reply with quote

Where does the amd fx-8350 fit into this?
Back to top
View user's profile Send private message
_______0
Guru
Guru


Joined: 15 Oct 2012
Posts: 521

PostPosted: Sat May 04, 2013 3:45 pm    Post subject: Reply with quote

I wasn't talking about hypeardthreading in cpus but at to which cpu that option applies to.

[ ] SMT (Hyperthreading) scheduler support
Code:
 SMT scheduler support improves the CPU scheduler's decision making
  when dealing with Intel Pentium 4 chips with HyperThreading at a
   cost of slightly increased overhead in some places. If unsure say
   N here.


So for AMD the second one:

[*] Multi-core scheduler support
Back to top
View user's profile Send private message
Hu
Moderator
Moderator


Joined: 06 Mar 2007
Posts: 21489

PostPosted: Sat May 04, 2013 4:46 pm    Post subject: Reply with quote

Kernel help text, although useful, is sometimes out of date. Do you have a more definitive reference for that feature applying only on Pentium4 chips? I see nothing in the kernel source for SMT handling that appears to restrict it to Pentium4 chips.
Back to top
View user's profile Send private message
Display posts from previous:   
Reply to topic    Gentoo Forums Forum Index Kernel & Hardware All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum