Re: [Boost-bugs] [Boost C++ Libraries] #12248: boost::log::attributes:timer accuracy shift

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #12248: boost::log::attributes:timer accuracy shift
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-07-17 15:07:41

#12248: boost::log::attributes:timer accuracy shift
-------------------------------+-----------------------
  Reporter:  tib               |      Owner:  andysem
      Type:  Bugs              |     Status:  closed
 Milestone:  To Be Determined  |  Component:  log
   Version:  Boost 1.61.0      |   Severity:  Problem
Resolution:  invalid           |   Keywords:  log timer
-------------------------------+-----------------------
Changes (by andysem):

 * status:  new => closed
 * resolution:   => invalid

Comment:

 I believe your `PreciseTimer` is less precise than the timer the library
 offers. In particular, your code involves FP operations on the number of
 ticks since the timer construction:

 {{{
 double e = (nowCounter.QuadPart - m_startCounter.QuadPart) / (double)
 m_freq.QuadPart;
 }}}

 As the difference grows, the precision of `double` becomes insufficient.

 The library code is also faster since it avoids division in the hot path.
 I admit, the implementation could be made more precise if 128-bit integer
 math was used instead of FP math, but I suspect it would be much slower
 yet.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/12248#comment:1>
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