Re: boost high precision timer and boost io_service

From: Bjorn Reese (breese_at_[hidden])
Date: 2019-08-22 08:05:34

On 8/22/19 3:55 AM, JH via Boost wrote:

> Yes, I am doing the experiment to increase process priority, it will
> help, but don't know how much. I am not quite sure if replace
> boost::asio::deadline_timer by high_resolution_timer will help or not,
> or if multithreading will help, the device is running simple process

It is not only a matter of processing priority. Your data can also be
delayed because the network is busy.

However, I suspect that your main problem is not so much that a single
timeout is delayed, but rather that a delay causes a shift in the
subsequent timeouts. In that case you could measure the time between
two timeouts, and then compensate for any deviations by making the
next expiration time accordingly shorter or longer.

In other words, you want a sequence of expiration time like this:

   T + 1 * delta
   T + 2 * delta
   T + 3 * delta
   T + 4 * delta

but because of delays you are actually getting have an accumulated
error:

   T + 1 * delta
   T + 2 * delta + error
   T + 3 * delta + error
   T + 4 * delta + error

With compensation you will get:

   T + 1 * delta
   T + 2 * delta + error
   T + 3 * delta - error (this is the compensation step)
   T + 4 * delta