Question about JDK-8221092

[Taizo Kurashige (Fujitsu)]

Hi all,

I'm sorry to bother you again.
If possible, could anyone please give me some insight on the following?

Is there a specification for what the stepping value is for a particular processor? For example, is it defined in any documentation that CascadeLake processors have stepping >=5?
I searched the documentation provided by Intel but couldn't find it.

I want some evidence that the following is true.
・All Skylake processors have stepping < 5
・CascadeLake processors have stepping >=5.

Thanks.

----------------------------------------------------------------------------------------
Taizo Kurashige
GitHub account : https://github.com/kurashige23


________________________________

Hi all,

I'm sorry to bother you again.
If possible, could anyone please give me some insight?

Thanks.

----------------------------------------------------------------------------------------
Taizo Kurashige
GitHub account : https://github.com/kurashige23


________________________________
 Hi all,

If possible, could anyone give me some insight?

Thanks.

----------------------------------------------------------------------------------------
Taizo Kurashige
GitHub account : https://github.com/kurashige23


________________________________

Hi Sandhya,

Thank you for your response.

Thanks to you, I understood the following.
・All Skylake processors have cupid family=6, model=0x55, stepping < 5
・CascadeLake processors have cupid family=6, model=0x55, stepping >=5.


If possible, I would like you to tell me about the following.

Is there a specification for what the stepping value is for a particular processor? For example, is it defined in any documentation that CascadeLake processors have stepping >=5?
I searched the documentation provided by Intel but couldn't find it.

I want some evidence that the following is true.
・All Skylake processors have stepping < 5
・CascadeLake processors have stepping >=5.

If stepping per processor is specified somewhere, please let me know.

Thanks.

----------------------------------------------------------------------------------------
Taizo Kurashige
GitHub account : https://github.com/kurashige23

________________________________

Hi Taizo,

UseAVX is set to 2 for all Skylake processors (cupid family=6, model=0x55, stepping < 5) , not just Skylake X.
CascadeLake processors have cupid family=6, model=0x55, stepping >=5.

Hope this helps.

Best Regards,
Sandhya

-------- Forwarded Message --------
Subject:         Re: Question about JDK-8221092
Date:    Wed, 10 Jul 2024 06:39:43 +0000
From:    Taizo Kurashige (Fujitsu) <kurashige.taizo at fujitsu.com>
To:      hotspot-compiler-dev at openjdk.org <hotspot-compiler-dev at openjdk.org>



Hi all,

Could someone please respond to this question if possible?

Thank you.

----------------------------------------------------------------------------------------
Taizo Kurashige
GitHub account : https://github.com/kurashige23 <https://github.com/kurashige23>
------------------------------------------------------------------------------------------------------------------------
*差出人:* Kurashige, Taizo/倉繁 泰三
*送信日時:* 2024年7月3日 15:09
*宛先:* hotspot-compiler-dev at openjdk.org <hotspot-compiler-dev at openjdk.org>
*件名:* Question about JDK-8221092
Hi all,
I have a question about https://bugs.openjdk.org/browse/JDK-8221092.
If possible, could someone please provide some insight?

Here's what I would like to know:

1. Is it correct to understand that "Skylake (X7) processors" refers to the Skylake processors listed at https://ark.intel.com/content/www/us/en/ark/products/codename/37572/products-formerly-skylake.html, specifically those in the 7000 series with an "X" or "XE" in their names? For example, "Intel® Core™ i9-7920X X-series Processor (16.5M Cache, up to 4.30 GHz)" or "Intel® Core™ i9-7980XE Extreme Edition Processor (24.75M Cache, up to 4.20 GHz)".

2. In the fix for JDK-8221092, if the stepping is less than 5, the processor is considered to be of Skylake (X7) or an earlier version. In such cases, UseAVX is set to 2. Is there any documentation that the stepping for Skylake (X7) is 5?

Thank you.


----------------------------------------------------------------------------------------
Taizo Kurashige
GitHub account : https://github.com/kurashige23 <https://github.com/kurashige23> <https://github.com/kurashige23>

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