Re: [PATCH] pgbench --throttle (submission 7 - with lag measurement)

Greg Smith wrote:

Thanks.  I didn't look at the code, but while trying to read the docs:

> +        <para>
> +         High rate limit schedule lag values, that is values not small with
> +         respect to the actual transaction latency, indicate that something is
> +         amiss in the throttling process.

I couldn't really parse the above.  Of the first six words, which one is
a verb?  Is there a noun that needs to be plural?  Is there a word that
shouldn't be there?

... Oh, I think it makes sense if I assume that "rate limit schedule lag"
is a single concept .. but if so, that phrase seems too many words for it.
(So when the RLSL values are high, this indicates a problem.  Is that
what the above means?)

Also, it took me a while to understand what "values not small" means.  I
think there must be a way to phrase this that's easier to understand.

>                                            High lag can highlight a subtle
> +         problem there even if the target rate limit is met in the end.  One
> +         possible cause of schedule lage is insufficient pgbench threads to
> +         handle all of the clients.

typo "lage" above.

>                                       To improve that, consider reducing the
> +         number of clients, increasing the number of threads in pgbench, or
> +         running pgbench on a separate host.  Another possibility is that the
> +         database is not keeping up with the load at some point.  When that
> +         happens, you will have to reduce the expected transaction rate to
> +         lower schedule lag.
> +        </para>

Thanks

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Álvaro Herrera                http://www.2ndQuadrant.com/
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