[Development] QMutex on Windows

Thiago Macieira thiago.macieira at intel.com
Thu Aug 23 17:49:31 CEST 2012


Here are the partial results for Windows:
https://docs.google.com/spreadsheet/pub?key=0AvVqQ9a3_pIudExQek1hOXRyTVVZZ0tMN1kzQjdhNGc&gid=1

Just like on Linux, the new QMutex is much worse than native and than Qt 4.8 
for the contended case. Both contention cases are showing 700% worse than 
Windows native. On Linux, the 1-mutex case was 100% worse but the 2-mutex case 
was 1000%.

I haven't been able to test the new code yet because tst_QMutex crashes 
immediately with a failed assertion. I'll need to debug this tomorrow.

Reference:
Intel i5-560M (Westmere)
	2 cores x 2 threads, 2.66 GHz, turbo 3.0 GHz
	CPU in "performance" mode
Windows 7
MSVC 2010, 64-bit mode
QtCore in release mode, using the standard compilation flags

Results are either the best of 6 runs, or the second best of 9 runs.

PS: I'm quite impressed by the performance of the native solution. The only 
thing is that the benchmark is not testing the Win32 functions we're using in 
QMutex...
-- 
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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