Re: How to increase maximum user cpu usage allowed on a multi core system?

Re: How to increase maximum user cpu usage allowed on a multi core system?

[poma]

On 09.03.2015 20:03, stan wrote:
> I'm running Fedora 21 with a custom compiled kernel,
> 3.19.0-1.20150211.fc21.x86_64.
> 
> I have a multi core system with 6 cores.  All are recognized by the
> kernel.  
> 
> But, when I run a compile job with -j6, in order to allow all six cores
> to be used, it limits the total amount of usage to 100% of a *single*
> core.  So, it might use all six cores, but the sum of the percentages
> on those six cores is always around 100% of one core.  This is from
> htop output.
> 
> On large compilations, like the kernel or firefox, even using 4 cores
> could drastically reduce compile time.
> 
> I've looked at /etc/security/limits.conf, but it doesn't seem to have a
> setting for this.  I've also looked at the /proc system to see if there
> is a kernel variable, though that seems unlikely, with no luck.  Online
> searching found ways to limit the amount that a single job can get, but
> not how to set this for a user.  There must be a configuration variable
> somewhere that is limiting the amount of total cpu a user can use.  But
> I can't find it.
> 
> Can anyone help?
> 


Borislav, can you help explain the man why this is happening with his Piledriver.
http://www.cpu-world.com/CPUs/Bulldozer/AMD-FX-Series%20FX-6300.html


poma

Re: How to increase maximum user cpu usage allowed on a multi core system?

[Borislav Petkov]

On Tue, Mar 17, 2015 at 07:34:08PM +0100, poma wrote:
> On 09.03.2015 20:03, stan wrote:
> > I'm running Fedora 21 with a custom compiled kernel,
> > 3.19.0-1.20150211.fc21.x86_64.
> > 
> > I have a multi core system with 6 cores.  All are recognized by the
> > kernel.  
> > 
> > But, when I run a compile job with -j6, in order to allow all six cores
> > to be used, it limits the total amount of usage to 100% of a *single*
> > core.  So, it might use all six cores, but the sum of the percentages
> > on those six cores is always around 100% of one core.  This is from
> > htop output.

Let me try to understand this correctly?

You're building the kernel with

make -j6

but in htop you're seeing a single core at 100% and the rest are idle?
Yes, no?

What exact steps are you doing to build the kernel? Type them here
please so that I can do them exactly on my system too.

Also, please send a full dmesg from your system, private message is fine
too.

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--