Re: [PATCH] check kernel version for io_method

Le 14/01/2026 à 08:31, Steven Niu a écrit :
> From: Andreas Karlsson <andreas(at)proxel(dot)se>
> Sent: Wednesday, January 14, 2026 15:27
> To: Steven Niu <niushiji(at)gmail(dot)com>; Pierre <pierre(dot)forstmann(at)gmail(dot)com>; pgsql-hackers(at)lists(dot)postgresql(dot)org <pgsql-hackers(at)lists(dot)postgresql(dot)org>
> Subject: Re: [PATCH] check kernel version for io_method
>
>
> On 1/14/26 8:22 AM, Steven Niu wrote:
>> I agree that you are correct for now. But in future, the IoMethod may have new member. Then we have to process it.
>>
>> How about change to like this:
>>    + #else
>>    +     if (*newval == IOMETHOD_IO_URING)
>>    +     {
>>    +             GUC_check_errdetail("io_uring not enabled.");
>>    +             return false;
>>    +     }
> No, that would be incorrect. It would not even compile.
> IOMETHOD_IO_URING is not even defined if we do not compile with liburing
> enabled. You can try it out yourself by compiling PostgreSQL without
> io_uring support and then try to enable it. You will get an error and
> that code will never be reached.
>
> Andreas
>
>
>
>
> ________________________________________
>
>
> Yes, you are definitely correct.
> I'd like to withdwar my proposal.

Hello,

I have modified message in case io_uring is not enabled when building
PG. But currently I cannot test it, GUC parameter is rejected in earlier
steps:

pg_ctl start
waiting for server to start....2026-01-14 09:35:37.046 GMT [16336] LOG: 
invalid value for parameter "io_method": "io_uring"
2026-01-14 09:35:37.046 GMT [16336] HINT:  Available values: sync, worker.
2026-01-14 10:35:37.047 CET [16336] FATAL:  configuration file
"/home/pierre/pgdata/postgresql.conf" contains errors
 stopped waiting
pg_ctl: could not start server

I don't know how to test io_uring features in code because if io_uring
is not enabled at compilation time, I don't think it is possible to
compile code calling  io_uring_get_probe_ring() or
io_uring_opcode_supported() ?

Thanks.