From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tobias Oberstein <tobias.oberstein@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org
Subject: Re: lseek/read/write overhead becomes visible at scale ..
Date: Tue, 24 Jan 2017 15:36:13 -0300
Message-ID: <20170124183613.cbb47nqbvso4rvjb@alvherre.pgsql> (raw)
In-Reply-To: <a55b21d1-7c99-2c66-d661-ef5288f29e30@gmail.com>
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Tobias Oberstein wrote:
> I am benchmarking IOPS, and while doing so, it becomes apparent that at
> these scales it does matter _how_ IO is done.
>
> The most efficient way is libaio. I get 9.7 million/sec IOPS with low CPU
> load. Using any synchronous IO engine is slower and produces higher load.
>
> I do understand that switching to libaio isn't going to fly for PG
> (completely different approach).
Maybe it is possible to write a new f_smgr implementation (parallel to
md.c) that uses libaio. There is no "seek" in that interface, at least,
though the interface does assume that the implementation is blocking.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, tobias.oberstein@gmail.com, andres@anarazel.de
Subject: Re: lseek/read/write overhead becomes visible at scale ..
In-Reply-To: <20170124183613.cbb47nqbvso4rvjb@alvherre.pgsql>
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