Message-ID: <10a90d37-3471-4ea4-a492-117c7997d4ed@proxel.se>
Date: Wed, 14 Jan 2026 18:26:27 +0100
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Subject: Re: [PATCH] check kernel version for io_method
To: Jakub Wartak <jakub.wartak@enterprisedb.com>,
 Steven Niu <niushiji@gmail.com>
Cc: Pierre <pierre.forstmann@gmail.com>,
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 <CAKZiRmy3xrsju81b-fzUjtwn_dHR-744eJ31KYzo8hiyGnxMBA@mail.gmail.com>
From: Andreas Karlsson <andreas@proxel.se>
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On 1/14/26 12:14 PM, Jakub Wartak wrote:
> I haven't looked at this patch, however the above statement is not
> completely true. There is a parallel problem [1] related to kernel
> version, where if you do not run proper kernel version (>= 6.5) or
> proper liburing version, then fork() (-> all connections established)
> are going to be slow slugging under more than basic load due to lack
> of "combined memory mapping creation" (so technically speaking
> recommending someone to go to 5.6.x but < 6.5 IMHO is also not good
> advice). See first message in that [1] for a performance report about
> this. IMHVO if we are checking for kernel versions we could also warn
> about performance regression (something like merge those two patches
> if one wants to have a good io_uring experience).

We can probe for that too, which we already do. If you call 
pgaio_uring_ring_shmem_size() it will return 0 on Linux <6.5. Which I 
think eve further supports probing for the features we need rather than 
looking at the kernel version.

Andreas