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

On 03/30 06:17, james wrote:
> On 3/28/20 9:24 AM, tuxic@××××××.de wrote:
> > 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
>
> Meino,
>
> You might like the organization and details of
>
> "sys-process/htop"
>
> to look at cores and processes.
>
>
> hth,
> James
>
>

James,

...is a companion of mine for a long time already - thanks
for your help!

Meino