> -----Original Message----- > From: Kai Tietz [mailto:[email protected]] > Sent: Tuesday, February 26, 2013 11:00 AM > To: [email protected] > Subject: Re: [Mingw-w64-public] SJLJ vs DW2 - fact checking > > Hello Kai, > > 2013/2/26 Koehne Kai <[email protected]>: > > Hi there, > > > > For Qt 5.0 we've been packaging a 32bit mingw-builds toolchain with SJLJ > exception handling. However, it now became clear that the performance > penalty for SJLJ is quite heavy (e.g. 25% for startup of a medium-sized > application, up to 3x slow down for a small test application, see also > https://bugreports.qt-project.org/browse/QTBUG-29653 ). I'm therefore > inclined to recommend a switch to a DW2 based version for Qt 5.1. > > Hmm, it is true that SjLj is slower as table-based unwind-information. > That mainly caused by the need of actual executing code for it, even if > exception wasn't thrown. So I am bit curious why there is a penalty of 25% > on startup. An average execution-penalty of 5-10% I might could > understand. Could you describe in more detail what "startup" actual means?
Hi Kai :) As described in the other mail the startup times are the time between the first debugger log entry, and the last entry, when starting qt creator 2.6.2 with C:\> bin\qt-creator -profile -settingspath some-inexisting-dir What happens during startup that around 75 .dlls (Qt dlls and creator plugins) are loaded. Every plugin also initializes itself by e.g. checking for settings on the filesystem, creating objects etc. There's some variation in the results, probably due to file system access times / other processes kicking in, but even the slowest startup time measured for the dw2 based creator (1,301 ms) was still faster than the fastest startup for the sjlj compiled creator (1,493 ms). I'm open to trying other benchmarks if anyone has an idea :) Regards Kai ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Mingw-w64-public mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
