[Development] Container refactor update [Caution: Message contains Suspicious URL content]

[Thiago Macieira]

On quinta-feira, 21 de junho de 2012 09.56.39, Mülner, Helmut wrote:
> I measured this programming using MSVC2010 with /Ox and Rational Quantify
> and also the a 3:1 factor. But: QList::append calls new 10000 times,
> QVector::append never calls new but QVectorData::allocate twice and
> QVector::realloc once. If I add f.reserve(10000) in both cases,
> QList::append still call new 10000 times, and QVectorData::allocate is
> still called only twice, and QVector is faster than QList (by a small but
> consistent margin). Without optimization QVectorData::allocate is call 24
> times (for the first case, still 3:1).

Technically, QVector is also calling operator new and if you don't reserve the 
size beforehand, then it's probably calling new much more than 10000 times.

The difference is that it's calling the placement operator new, which does not 
allocate memory.

QList's performance will be better if your class's (copy) constructor is 
expensive.
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
     Intel Sweden AB - Registration Number: 556189-6027
     Knarrarnäsgatan 15, 164 40 Kista, Stockholm, Sweden
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