New subject: substantial lag time difference from boost::thread 1.57 and 1.60

8 Jul 2016

      Hello,
I am an engineer in a neurosciences lab. We have some data acquisition 
software that uses boost::thread and some other boost libraries as well. 
Part of my job is to measure the lag time for our devices' data 
acquisition. I have been testing the acquisition software when linking 
against boost v.1.57.0 and v.160.0.

Basically I generate a test signal and read it in with an NIDAQ and our 
EEG system. The signal is a series of 3ms long pulses. When the input to 
the NIDAQ goes high, I generate a timestamped marker. Meanwhile the EEG 
system is getting the same pulse train input and I record that digital 
data on its own thread and timestamp that as well. Then I compare the 
timestamps at which the EEG signal has a rising edge with the timestamps 
of the markers. The difference between these time values is the lag of 
the EEG system.

The app I use to get the EEG signal uses boost::thread. The lag time is 
consistently ~2.7 ms when linking against boost v.1.57.0 and is a 
whopping 11.6 ms when I link against v.1.60.0. Since the data 
acquisition happens in a tight loop on its own thread, I am guessing 
that there is some kind of increased latency of boost threads in newer 
versions of the library.

Does anybody know what might be causing this? I am on Windows 7, 64-bit 
and am using the pre-compiled boost libraries (i.e. I am not compiling 
them myself).

Cheers,
David

substantial lag time difference from boost::thread 1.57 and 1.60

David Medine

Michael Powell

David Medine

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