Re: [PATCH] add --throttle option to pgbench

On 4/29/13 1:08 PM, Fabien COELHO wrote:
>
>> While I don't understand the part about his laptop battery, I think that
>> there is a good use case for this. If you are looking at latency
>> distributions or spikes, you probably want to see what they are like with a
>> load which is like the one you expect having, not the load which is the
>> highest possible. Although for this use case you would almost surely be
>> using custom transaction files, not default ones, so I think you could just
>> use \sleep. However, I don't know if there is an easy way to dynamically
>> adjust the sleep value by subtracting off the overhead time and randomizing
>> it a bit, like is done here.
>
> Indeed, my thoughts:-) Having regularly (\sleep n) or uniformly distributed (\sleep :random_value) is not very realistic, and I would have to do some measures to find the right value for a target load.

+1 to being able to throttle to make latency measurements.

I'm also wondering if it would be useful to be able to set a latency target and have something adjust concurrency to see how well you can hit it. Certainly feature creep for the proposed patch; I only bring it up because there may be enough similarity to consider that use case at this time, even if we don't implement it yet.
--
Jim C. Nasby, Data Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net