[hpsdr] CPU utilization percentages, and how they can mislead

[George Byrkit]

Ari,
No, the cores do not intrinsically share the load!  That only happens if for example all
the apps are multi-thread aware, and do not set thread affinity so the threads run on the
same core.  I think that the performance meter shows the total CPU usage.  100% would be
all cores maxed out.

George

-----Original Message-----
From: Ari Þórólfur [mailto:ari at ice.is] 
Sent: Thursday, March 31, 2016 6:14 AM
To: 'George Byrkit'; hpsdr at lists.openhpsdr.org
Subject: RE: [hpsdr] CPU utilization percentages, and how they can mislead

Hi
I have 12 Core I7 and with 10% load, all core share the load, not just one
core ?
When I look at Performance, I see no CPU go over 30 %    or up to 100%

TF3ARI


-----Original Message-----
From: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of George
Byrkit
Sent: mánudagur, 28. mars 2016 20:17
To: hpsdr at lists.openhpsdr.org
Subject: [hpsdr] CPU utilization percentages, and how they can mislead

***** High Performance Software Defined Radio Discussion List *****

I would like to point out that if you have a 'quad-core' CPU (like an Intel
I7), which has
8 virtual cores, if you max out one core, that is 12.5% CPU utilization!
Throw in a little more for the other cores doing things, like running Task
Manager, and you'll be around 16% or so.  You think: 'I am fine!  I have 84%
free cycles.  What could be wrong with that?'.  Well, you could be in worse
shape than you think!

You think that you have 'plenty of CPU to spare', but one core might be
totally saturated, with no spare cycles, and whatever is using that core is
CPU-bound, because it is a simple application with simple CPU core
assumptions or utilization.

73,
George K9TRV

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