Date: Thu, 24 Aug 2006 14:00:29 -0500 From: Josh Paetzel <josh@tcbug.org> To: freebsd-stable@freebsd.org Cc: Laurent C <laurent.bar@gmail.com> Subject: Re: [AMD64-SMP] I can't get my cpus working at 100% Message-ID: <200608241400.29903.josh@tcbug.org> In-Reply-To: <e92de5ef0608241109x2aa5b79u32a4e304d34f29d5@mail.gmail.com> References: <e92de5ef0608241109x2aa5b79u32a4e304d34f29d5@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thursday 24 August 2006 13:09, Laurent C wrote: > Hello all, > > I can't get my athlon x2 processor working at 100% on cpu-intensive > apps. I've made some tests with "john --test" and "transcode", wich > are both multithreaded apps. > > For example if I launch transcode it takes between 50% and 55% cpu > (on top), and if I launch > a second transcode session on another file, the total cpu used on > top is 100%, without lower the speed > of the first transcode session. > > The same behavior occurs with john. A single "john --test" give me > some speed results, and the same > command with a transcode or second "john --test" give me the same > speed results but now with 100% > cpu used. > > I made a "portupgrade -auf" just after building and installing my > SMP kernel and World, to be sure all is up-to-date. > > So it's seems it's not a "top" output problem, but a real underuse > of the computing power. > > %uname -a > FreeBSD wks02.chez.oim 6.1-STABLE FreeBSD 6.1-STABLE #0: Thu Aug 17 > 18:47:31 CEST 2006 > laurent@wks02.chez.oim:/usr/obj/usr/src/sys/WKS02_SMP amd64 > > Does anyone could explain me what's happening with my system ? An application that is not written to take advantage of a multi-cpu system is unable to max out more than one CPU at a time. top isn't really SMP 'aware' so in a dual CPU system something that is using 50% of the CPU is in reality maxing one CPU. This is a bit over-simplified because the process will bounce between the two CPUs but it will never execute on more than one at a time. -- Thanks, Josh Paetzel
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200608241400.29903.josh>