Re: Group Commit - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Group Commit
Date
Msg-id 23398.1175185564@sss.pgh.pa.us
Whole thread Raw
In response to Group Commit  (Heikki Linnakangas <heikki@enterprisedb.com>)
Responses Re: Group Commit  (Heikki Linnakangas <heikki@enterprisedb.com>)
List pgsql-hackers
Heikki Linnakangas <heikki@enterprisedb.com> writes:
> I've been working on the patch to enhance our group commit behavior. The 
> patch is a dirty hack at the moment, but I'm settled on the algorithm 
> I'm going to use and I know the issues involved.
> ...
> The timeout is currently hard-coded at 1 ms.

This is where my bogometer triggered.  There's way too many platforms
where 1 msec timeout is a sheer fantasy.  If you cannot make it perform
well with a 10-msec timeout then I don't think it's going to be at all
portable.

Now I know that newer Linux kernels tend to ship with 1KHz scheduler
tick rate, so there's a useful set of platforms where you could make it
work even so, but I'm not really satisfied with saying "this facility is
only usable if you have a fast kernel tick rate" ...
        regards, tom lane


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