Re: [PATCH v4 4/8] pdx: allow per-arch optimization of PDX conversion helpers

[Jan Beulich <jbeulich@xxxxxxxx>]

On 05.08.2025 16:20, Roger Pau Monné wrote:
> On Tue, Aug 05, 2025 at 02:11:22PM +0200, Jan Beulich wrote:
>> On 05.08.2025 11:52, Roger Pau Monne wrote:
>>> There are four performance critical PDX conversion helpers that do the PFN
>>> to/from PDX and the physical addresses to/from directmap offsets
>>> translations.
>>>
>>> In the absence of an active PDX compression, those functions would still do
>>> the calculations needed, just to return the same input value as no
>>> translation is in place and hence PFN and PDX spaces are identity mapped.
>>>
>>> To reduce the overhead of having to do the pointless calculations allow
>>> architectures to implement the translation helpers in a per-arch header.
>>> Rename the existing conversion functions to add a trailing _xlate suffix,
>>> so that the per-arch headers can define the non suffixed versions.
>>>
>>> Currently only x86 implements meaningful custom handlers to short circuit
>>> the translation when not active, using asm goto.  Other architectures use
>>> generic macros that map the non-xlate to the xlate variants to keep the
>>> previous behavior.
>>>
>>> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>>
>> Once again:
>> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Thanks, I didn't carry your RB due to the changes requested by Andrew,
> that was a bit too much to carry a RB after those.

Of course, and I didn't mean to suggest you should have kept it. All I
wanted to indicate is that I'm as okay withe change as I was before.

Jan