Mail Archives: cygwin/2005/05/28/17:04:51
Christopher Faylor wrote:
> On Sat, May 28, 2005 at 01:24:31PM +0200, Vaclav Haisman wrote:
>
>>Somebody mentioned that malloc implementation could be the problem. Dunno. I
>>has also crossed my mind that another difference between FreeBSD and Cygwin is
>>implementation of C++ exceptions. Maybe the SJLJ implementation that Cygwin
>>AFAIK uses has too big overhead.
>
>
> To test this theory, I just tried replacing Cygwin's "Unwind" functions
> with those from mingw and saw a noticeable speed up in the execution of
> this program. I did this by extracting the contents of mingw's libgcc
> to a directory and then including unwind-c.o and unwind-sjlj.o on the
> command line when linking the test case. I had to modify the test case
> by adding these two lines to the bottom:
>
> int __mingwthr_key_dtor;
> int _CRT_MT;
>
> to avoid undefined symbol errors so this is obviously not intended as a
> complete solution.
>
> On doing this, the program went from taking 25 seconds to execute to
> taking 7 seconds to execute. That's still 4x slower than mingw but it
> is, nonetheless, a noticeable difference.
Wow, this is really worth to investigate.
> Gerrit and Danny do you know what the difference between the mingw and
> cygwin implementations of these functions might be?
A quick look shows that there are basically no differences in these two
files, but there a functions called which are defined in
w32-shared-ptr.c, can you include this as well, please?
These parts are Cygwin only:
#ifdef __CYGWIN__
static void __w32_sharedptr_fixup_after_fork (void);
#endif
[...]
#ifdef __CYGWIN__
/* recreate atom after fork */
pthread_atfork (NULL,NULL,__w32_sharedptr_fixup_after_fork);
#endif
[...]
#ifdef __CYGWIN__
static void __w32_sharedptr_fixup_after_fork (void)
{
if (!__w32_sharedptr_set (__w32_sharedptr))
abort ();
}
#endif
All the rest (in unwind-*) is shared. So the Cygwin version is slower
for sure. I don't know why this is needed for Cygwin and not for MinGW,
Danny?
Gerrit
--
=^..^=
--
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Problem reports: http://cygwin.com/problems.html
Documentation: http://cygwin.com/docs.html
FAQ: http://cygwin.com/faq/
- Raw text -