E3930 Processor Frequency stability

[sandeepvangala]

Hi Team,

We are testing a total of 16 cards, of which 4 are operating at 1.3/1.4GHz, 4 are running at 1.8GHz, 2 are running at 1.7GHz,
and 2 are running at 1.5GHz. How may the CPU Can differ? 
CPU swapping is not possible as all are BGA manufactured. If all are working at the same frequency and one or two are exhibiting this behavior,
it may indicate a CPU issue, which can be addressed by swapping.

To clarify, I'd like to include additional detail on the behaviour of performing/non-performing cards.
When we perform CPU-intensive programmes. This is the behaviour of a performing or non-performing card.
In all cases,We are running ubuntu OS and the default CPU frequency before the test is 800MHz(from /proc/cpuinfo).
In the performing card, the CPU starts working at 1800MHz initially and continues to work above 1700MHz .
In non-performing cards, the CPU first starts to runs at 1800MHz before dropping to 1350MHz (1500MHz on some boards) while executing.

Due to this graphics performance also reducing to 1/4.

When we are probing core voltage it is differ for each frequency and this information is sent by processor itself. 

Where could be the problem??

-Regards,

Sandeep V

[NormanS_Intel]

Hello sandeepvangala,

Thank you for posting in the community!

To ensure you receive the most specialized assistance, we have a dedicated forum that addresses these specific concerns. Therefore, I will be moving this discussion to our Embedded Forum. This will allow our knowledgeable community and experts to provide you with timely and accurate solutions.

Best regards,

Norman S.

Intel Customer Support Engineer

[sandeepvangala]

Hi Norman S,

Kindly move to respected forum so that we can get answer for this.

-Regards,

Sandeep V

[Diego_INTEL]

Hello @sandeepvangala 

Thank you for contacting Intel Embedded Community.

Please consider that Apollo Lake is not actively supported anymore, as you can check in this link:

https://www.intel.com/content/www/us/en/support/articles/000022396/processors.html

I was checking but it seems a normal behavior, the base frequency for this processor is 1.3 GHz while in Burst frequency is up to 1.8 GHz.

https://www.intel.com/content/www/us/en/products/sku/96486/intel-atom-x5e3930-processor-2m-cache-up-to-1-80-ghz/specifications.html

I'm taking this from the Elkhart Lake documentation but it applies here too:

"Intel® Burst Technology allows processor IA cores to run faster than the base frequency. It is invoked opportunistically and automatically as long as the processor is conforming to its temperature, power delivery and current control limits."

What you may expect is the base frequency, so it is normal that they get working at a frequency of 1.3 GHz and the higher frequency values may be used opportunistically and frequency is used only for short periods.

Best regards,

@Diego_INTEL 

[sandeepvangala]

Thank you for the reply,

We are monitoring CPU frequency and graphical performance under the same settings and hardware configuration. We have a set of non-performing and performing cards. When we measure the graphics draw time in the performing cards, it takes 8ms, whereas in the non-performing cards, it takes 35 ms or more to draw the same graphics page (which is not acceptable for the application by our end customer). We know that graphics performance is related to graphics processing unit, but we can see that graphics performance also degrades in the same way, when CPU frequency does.

We can find voltage in pmic drop from 1.05 to .8 Volt in non-performing cards, when it change to base frequency 1.3GHz or below, While it stays constant 1.05 volt in the performing card and frequency of processor above base frequency 1.5GHz +. 

We need to identify where the problem is ? in the side of Processor or PMIC ?

Pointers to start debugging, where the problem could be ?

We are using IDT P91E0A-I5NHGI as per juniper hill design.

Best Regards,

[Diego_INTEL]

Hello @sandeepvangala 

Maybe you can try using  PTU to add the same load and get better comparison results:

#568714 - Intel® Power Thermal Utility (Intel® PTU) for Apollo Lake-I SoC and Windows* OS 10

Best regards,

@Diego_INTEL