Date: Mon, 9 May 2005 18:52:33 -0400 From: Suleiman Souhlal <ssouhlal@FreeBSD.org> To: Daniel Eischen <deischen@FreeBSD.org> Cc: freebsd-stable <freebsd-stable@FreeBSD.org> Subject: Re: Performance issue Message-ID: <4D923762-6562-440B-8456-EA404F7FDA44@FreeBSD.org> In-Reply-To: <Pine.GSO.4.43.0505091546540.27904-100000@sea.ntplx.net> References: <Pine.GSO.4.43.0505091546540.27904-100000@sea.ntplx.net>
next in thread | previous in thread | raw e-mail | index | archive | help
Hello, On May 9, 2005, at 3:54 PM, Daniel Eischen wrote: > On Tue, 10 May 2005, Peter Jeremy wrote: > > >> On Mon, 2005-May-09 11:00:18 -0400, Ewan Todd wrote: >> >>> I have what I think is a serious performance issue with fbsd 5.3 >>> release. I've read about threading issues, and it seems to me that >>> that is what I'm looking at, but I'm not confident enough to rule >>> out >>> that it might be a hardware issue, a kernel configuration issue, or >>> something to do with the python port. >>> >> >> There does appear to be a problem in FreeBSD. Python is built with >> threading enabled by default, the threading libraries play with the >> signal mask and there have been extensive changes there. My >> > > The threading libraries don't play with the signal mask. In fact, > libpthread has userland versions of sigprocmask() et. al. and won't > even make the syscall() unless the threads are system scope. There > is a special thread in libpthread that handles signals which does > use the system sigprocmask(), but unless the application is > making heavy use of signals in general, it shouldn't matter. 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. -- Suleiman Souhlal | ssouhlal@vt.edu The FreeBSD Project | ssouhlal@FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4D923762-6562-440B-8456-EA404F7FDA44>