Re: Don't synchronously wait for already-in-progress IO in read stream

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: pgsql-hackers(at)postgresql(dot)org, Tomas Vondra <tv(at)fuzzy(dot)cz>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
Subject: Re: Don't synchronously wait for already-in-progress IO in read stream
Date: 2025-11-09 19:51:08
Message-ID: CAH2-Wz=3_pmjM4=GLG+D2T=4uGm9dSMWbDTNzhHY3=kLoPPhaw@mail.gmail.com
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On Thu, Sep 11, 2025 at 5:46 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> The problem leading to that is that we are currently synchronously waiting for
> IO on a buffer when AsyncReadBuffers() encounters a buffer already undergoing
> IO. If a block is read twice, that means we won't actually have enough IOs in
> flight to have good performance. What's worse, currently the wait is not
> attributed to IO wait (since we're waiting in WaitIO, rather than waiting for
> IO).

This patch no longer cleanly applies. Can you post a new version?

Thanks
--
Peter Geoghegan

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