Re: [PATCH v2 3/3] docs: mm: add enable_soft_offline sysctl

[David Rientjes <rientjes@google.com>]

On Tue, 11 Jun 2024, Jiaqi Yan wrote:

> @@ -267,6 +268,20 @@ used::
>  These are informational only.  They do not mean that anything is wrong
>  with your system.  To disable them, echo 4 (bit 2) into drop_caches.
>  
> +enable_soft_offline
> +===================
> +Control whether to soft offline memory pages that have (excessive) correctable
> +memory errors.  It is your call to choose between reliability (stay away from
> +fragile physical memory) vs performance (brought by HugeTLB or transparent
> +hugepages).
> +

Could you expand upon the relevance of HugeTLB or THP in this 
documentation?  I understand the need in some cases to soft offline memory 
after a number of correctable memory errors, but it's not clear how the 
performance implications plays into this.  The paragraph below goes into a 
difference in the splitting behavior, are hugepage users the only ones 
that should be concerned with this?

> +When setting to 1, kernel attempts to soft offline the page when it thinks
> +needed.  For in-use page, page content will be migrated to a new page.  If
> +the oringinal hugepage is a HugeTLB hugepage, regardless of in-use or free,

s/oringinal/original/

> +it will be dissolved into raw pages, and the capacity of the HugeTLB pool
> +will reduce by 1.  If the original hugepage is a transparent hugepage, it
> +will be split into raw pages.  When setting to 0, kernel won't attempt to
> +soft offline the page.  Its default value is 1.
>  

This behavior is the same for all architectures?