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help / color / mirror / Atom feedFrom: Jelte Fennema-Nio <[email protected]>
To: Andres Freund <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: torikoshia <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Bruce Momjian <[email protected]>
Subject: Re: RFC: Allow EXPLAIN to Output Page Fault Information
Date: Tue, 11 Feb 2025 09:59:43 +0100
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On Tue, 11 Feb 2025 at 00:53, Andres Freund <[email protected]> wrote:
> > I mostly meant worker based AIO, yes. I haven't checked how accurately these
> > are kept for io_uring. I would hope they are...
>
> It does look like it is tracked.
nice!
> > The thing is that you'd often get completely misleading stats. Some of the IO
> > will still be done by the backend itself, so there will be a non-zero
> > value. But it will be a significant undercount, because the asynchronously
> > executed IO won't be tracked (if worker mode is used).
Yeah, makes sense. Like I said, I would be completely fine with not
showing these numbers at all/setting them to 0 for setups where we
cannot easily get useful numbers (and this bgworker AIO would be one
of those setups).
> Independent to of this, it's probably not good that we're tracking shared
> buffer hits after io combining, if I interpret this correctly... That looks to
> be an issue in master, not just the AIO branch.
You mean that e.g. a combined IO for 20 blocks still sounds only as 1
"shared read"? Yeah, that sounds like a bug.
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To: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
Subject: Re: RFC: Allow EXPLAIN to Output Page Fault Information
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