Performance issue
Daniel Eischen
deischen at freebsd.org
Mon May 9 16:47:10 PDT 2005
On Mon, 9 May 2005, Daniel Eischen wrote:
> On Mon, 9 May 2005, Suleiman Souhlal wrote:
> > I think I've found the problem: Python uses setjmp/longjmp to protect
> > against SIGFPU every time it does floating point operations. The
> > python script does not actually use threads, and libpthread assumes
> > non-threaded processes are system scope. So, it would end up using
> > the sigprocmask syscall, even though it doesn't really need to.
> > The diff at http://people.freebsd.org/~ssouhlal/testing/
> > thr_sigmask-20050509.diff fixes this, by making sure the process is
> > threaded, before using the syscall.
[ ... ]
> If the process wasn't linked to libpthread, then the longjmp()
> and setjmp() would still be calling the syscall, so it isn't
> the syscall itself that is making things slower. You'll notice
> that there are two calls to __sys_sigprocmask() in the section
> of code you have patched. You could eliminate the second call
> if you do some of what the remainder of the function does instead
> of returning early (the locks aren't needed and pending signals
> don't need to be run down).
As in something like this:
http://people.freebsd.org/~deischen/kse/thr_sigmask.c.diffs
It has not been tested.
--
DE
More information about the freebsd-stable
mailing list