Re: WIP: WAL prefetch (another approach) - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: WIP: WAL prefetch (another approach)
Date
Msg-id 20200606003632.GS6680@tamriel.snowman.net
Whole thread Raw
In response to Re: WIP: WAL prefetch (another approach)  (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
Responses Re: WIP: WAL prefetch (another approach)  (Thomas Munro <thomas.munro@gmail.com>)
List pgsql-hackers
Greetings,

* Tomas Vondra (tomas.vondra@2ndquadrant.com) wrote:
> I wonder if we can collect some stats to measure how effective the
> prefetching actually is. Ultimately we want something like cache hit
> ratio, but we're only preloading into page cache, so we can't easily
> measure that. Perhaps we could measure I/O timings in redo, though?

That would certainly be interesting, particularly as this optimization
seems likely to be useful on some platforms (eg, zfs, where the
filesystem block size is larger than ours..) and less on others
(traditional systems which have a smaller block size).

Thanks,

Stephen

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