Re: [gentoo-user] RYZEN 5: Hyperthreading or no hyperthreading...

On 03/28 05:59, Mark Knecht wrote:
> On Fri, Mar 27, 2020 at 10:58 PM <tuxic@××××××.de> wrote:
> >
> > On 03/27 11:51, Mark Knecht wrote:
> > > On Fri, Mar 27, 2020 at 11:11 AM <tuxic@××××××.de> wrote:
> > > >
> > > > On 03/27 06:04, Andrea Conti wrote:
> > > > > Hello,
> > > > >
> > > > > > Thread(s) per core:              1 <<<<<
> > > > > > Does my CPU hyperthread?
> > > > >
> > > > > Definitely not.
> > > > >
> > > > > Your kernel config is fine, chances are hyperthreading (aka "SMT
> mode")
> > > is
> > > > > disabled in your BIOS settings.
> > > > >
> > > > > andrea
> > > > >
> > > >
> > > > Hi Andrea,
> > > >
> > > > I checked that: The BIOS setting was set to use hyperthreading.
> > > >
> > > > But "Number of cores" was set to six. I changed that to 12 and
> > > > Voila! I got two threads per core.
> > > >
> > > > I think "Number of cores" is a little misleading, since there
> > > > are six physical cores (not threads) with a RYZEN 5.
> > > >
> > > > I feeling not that comfortable with this solution.
> > > >
> > > > Is there any way to check for the validity of this setting
> > > > beside a tool, which prints a "2" after the word "threads" ;) ?
> > > >
> > > > Cheers!
> > > > Meino
> > > >
> > > >
> > >
> > > cat /proc/cpu should give info for each thread. I've been running an i7
> 980
> > > Extreme processor @3.33GHz here at home for about 12 years or so. It's 6
> > > cores but shows 12 processors on both Gentoo and now Kubuntu.
> > >
> > > I generally run top and then hit '1' and 'z'. You can watch what
> percentage
> > > each core/thread is using.
> > >
> > > Time a BIG compile job twice, once with each kernel. If it's working
> you'll
> > > measure a significant difference in time. Note that it won't be 2x as
> > > you'll also be limited by disk read/write throughput, but you'll know
> it's
> > > basically working.
> > >
> > > On Gentoo make sure you're compile settings in (I think make.conf - I no
> > > longer run Gentoo much) are set to take advantage of all your cores and
> not
> > > limited to something smaller. Also watch overheating when using more
> > > cores/threads. On older PCs like mine when you possibly have dust in CPU
> > > coolers might not be as efficient as when they are new.
> > >
> > > HTH,
> > > Mark
> >
> > Hi Mark,
> >
> > thank you for your explanations! :)
> >
> > /proc/cpu doesn't exist on my system....may be you are referring to
> > /proc/cpuinfo?
> >
> > The problem was caused by a kernel misconfiguration by me.
> >
> > In the kernel setup there is a setting "Number of cores" which
> > I had set to six ... since my CPU has 6 physical core.
> >
> > Setting this to twelve (and blurring the syntactically border between
> > threads and cores thereby...) gives me twelves cores in top, htop
> > and such and (as an example) compiling the kernel is faster -
> > so it is not a display gimmick only.
> >
> > I think "Number of cores" is a misnomer...or am I wrong?
> >
> > Cheers!
> > Meino
> >
>
> Meino,
>    Yes, /proc/cpuinfo. Sorry.
>
>    Well yes, I guess the 'Number of cores' is a misnomer if you're trying
> to equate the language in the kernel against Intel/AMD marketing data for
> physical cores. 6 physical cores with or without hyperthreading is still 6
> physical cores. However 6 physical cores (my processor) _WITH_
> hyperthreading enabled is 12 _LOGICAL_ cores which is more what I think the
> kernel verbiage is about. Semantics I suppose.
>
>    I'm glad you found it wasn't a gimmicky number. It really does work,
> within the limits of the hardware being able to figure out what one thread
> should be fetching or writing while the other thread is computing. It's not
> a perfect 2:1 like 12 physical cores might be, but it's a lot less silicon
> and therefore a lot less expensive.
>
> Cheers,
> Mark

Hi Mark,

In the meanwhile I found "glance" and installed it, which is the
bazooka-out-of-the-box-no-configuration terminal-brethren of "conky"
:) 

Enough plugins enabled (which come with it preinstalled), you can
watch in realtime, what each core/thread is doing right now...nearly. Big
Brother for the sustem with no bad intention in mind. I am only
curious :)

And you get your sensors diplayed, the workload of your GPU (nvidia in 
my case), all processes and lot lot more. 

The faster the CPU gets (my previous PC was 12 years old...), the
more the peripheral devices are becoming show stoppers ("stoppers"
in the barest truth of its meaning).

Unfortunatelu the SSD I ordered is in status "ready for delivery"
since 23.03.2020....corona....you know...

And with 12 cores enabled on a recent CPU and running for example a
bigger update via emerge (enabled for 12 threads of course)
....all the cores are simply waiting a lot
faster......for the harddisc :)

Thanks for your help -- stay healthy!

Cheers!
Meino