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Re: [PATCH 1/4] xen: Introduce non-broken hypercalls for the p2m pool size


  • To: George Dunlap <dunlapg@xxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 31 Oct 2022 10:26:43 +0100
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  • Cc: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>, Roger Pau Monne <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Henry Wang <Henry.Wang@xxxxxxx>, Anthony Perard <anthony.perard@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>
  • Delivery-date: Mon, 31 Oct 2022 09:26:56 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 28.10.2022 17:27, George Dunlap wrote:
> On Thu, Oct 27, 2022 at 8:12 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
> 
>> On 26.10.2022 21:22, Andrew Cooper wrote:
>>> On 26/10/2022 14:42, Jan Beulich wrote:
>>
> 
> 
>>> paging isn't a great name.  While it's what we call the infrastructure
>>> in x86, it has nothing to do with paging things out to disk (the thing
>>> everyone associates the name with), nor the xenpaging infrastructure
>>> (Xen's version of what OS paging supposedly means).
>>
>> Okay, "paging" can be somewhat misleading. But "p2m" also doesn't fit
>> the use(s) on x86. Yet we'd like to use a name clearly better than the
>> previous (and yet more wrong/misleading) "shadow". I have to admit that
>> I can't think of any other sensible name, and among the ones discussed
>> I still think "paging" is the one coming closest despite the
>> generally different meaning of the word elsewhere.
>>
> 
> Inside the world of operating systems / hypervisors, "paging" has always
> meant "things related to a pagetable"; this includes "paging out to disk".
> In fact, the latter already has a perfectly good name -- "swap" (e.g., swap
> file, swappiness, hypervisor swap).
> 
> Grep for "paging" inside of Xen.  We have the paging lock, paging modes,
> nested paging, and so on.  There's absolutely no reason to start thinking
> of "paging" as exclusively meaning "hypervisor swap".

Just to clarify: You actually support my thinking that "paging" is an okay
term to use here? I ask because, perhaps merely because of not being a
native speaker, to me content and wording suggest different things: The
former appears to support my response to Andrew, while the latter reads to
me as if you were objecting.

Jan



 


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