Re: pgbench throttling latency limit

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
Cc: Rukh Meski <rukh(dot)meski(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pgbench throttling latency limit
Date: 2014-08-29 11:34:38
Message-ID: alpine.DEB.2.10.1408291252410.23808@sto
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Hello Heikki,

> This now begs the question:
>
> In --rate mode, shouldn't the reported transaction latency also be calculated
> from the *scheduled* start time, not the time the transaction actually
> started? Otherwise we're using two different definitions of "latency", one
> for the purpose of the limit, and another for reporting.

It could. Find a small patch **on top of v5** which does that. I've tried
to update the documentation accordingly as well.

Note that the information is already there as the average lag time is
reported, ISTM that:

avg latency2 ~ avg lag + avg latency1

so it is just a matter of choice, both are ok somehow. I would be fine
with both.

--
Fabien.

Attachment Content-Type Size
pgbench-limit-5b.patch text/x-diff 2.4 KB

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