| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tobias Oberstein <tobias(dot)oberstein(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: lseek/read/write overhead becomes visible at scale .. |
| Date: | 2017-01-24 18:36:13 |
| Message-ID: | 20170124183613.cbb47nqbvso4rvjb@alvherre.pgsql |
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| Lists: | pgsql-hackers |
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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