Re: Patch: add timing of buffer I/O requests

From: Dimitri Fontaine <dimitri(at)2ndQuadrant(dot)fr>
To: "Tomas Vondra" <tv(at)fuzzy(dot)cz>
Cc: "Greg Stark" <stark(at)mit(dot)edu>, "Greg Smith" <greg(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Patch: add timing of buffer I/O requests
Date: 2011-11-28 21:32:29
Message-ID: m2aa7gue4y.fsf@2ndQuadrant.fr
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"Tomas Vondra" <tv(at)fuzzy(dot)cz> writes:
> Another option would be to reimplement the vsyscall, even on platforms
> that don't provide it. The principle is actually quite simple - allocate a
> shared memory, store there a current time and update it whenever a clock
> interrupt happens. This is basically what Greg suggested in one of the
> previous posts, where "regularly" means "on every interrupt". Greg was
> worried about the precision, but this should be just fine I guess. It's
> the precision you get on Linux, anyway ...

That sounds good for other interesting things, which entails being able
to have timing information attached to the XID sequence. If we go this
way, how far are we from having a ticker in PostgreSQL?

Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support

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