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Re: wrong performance of malloc/free under multi-threading
On Feb 26 06:22, Chris J. Breisch wrote:
> On 2/26/2013 4:14 AM, Corinna Vinschen wrote:
> >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
> >
>
> Does any host using newlib suffer from this problem, or is it
> exclusive to Cygwin?
This is Cygwin only.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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