On Feb 26 15:35, MITSUNARI Shigeo wrote: > Hi. > > I found that the performance of malloc/free is wrong under multi-threading. > The following test program reproduces the problem. > > The program repeats malloc and free under multi-thread. > I measured the timing on Cygwin and Linux. > > timing(sec)| threadNum > -----------+----------+------------- > | 1 | 2 > -----------+----------+------------- > Linux | 1.45 | 0.69 > -----------+----------+------------- > Cygwin | 2.059 | 53.165 > -----------+----------+------------- > > The timing under Linux seems good scale but it is very wrong under Cygwin. > Is it intentional behavior or do I use pthread in bad way?
No, you're right. This is easily reproducable. I just had a look and it seems that our malloc is really slow in multi-threading scenarios. We're using Doug Lea's malloc unchanged with just additional locks surrounding the underlying malloc/free calls. This appears to be a serious performance problem. I just learned that glibc uses another version of dlmalloc, called ptmalloc, which is a derived version of dlmalloc optimized for multi-threading environments. Perhaps we have to do the same, but I don't know how long it takes to port ptmalloc to Cygwin and obviously I don't know how big the performance gain might be. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
