Re: [PATCH v2] powerpc/powernv: Cache OPAL check_token() results

[Nikhil Kumar Singh <nikhilks@linux.ibm.com>]

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I discussed this with Sourabh, and we confirmed this function is 
actually not on a hot path. However, he is open to the idea. Please take 
a look and see if adding unlikely() provides a meaningful benefit here, 
or if it falls into premature optimization.

Thanks
~ Nikhil

On 08/07/26 14:02, Shivang Upadhyay wrote:
> On Tue, 2026-07-07 at 12:36 +0530, Nikhil Kumar Singh wrote:
>> You can wrap the if (token_cache[token] == SUPP_UNKNOWN) check, as 
>> well as the if (token > OPAL_LAST) check above it, with unlikely(), 
>> since this function is in the hot path. Out-of-bounds tokens are very 
>> rare, and after the cache is populated, the SUPP_UNKNOWN condition is 
>> expected to be false in almost all cases. Wrapping these checks with 
>> unlikely() will help the compiler optimize branch
>
> Thanks for your suggestion, but Which hotpath code is calling this?
> we can maybe change that hotpath to not do rtas calls.
>
> ~Shivang.

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