Date: Fri, 31 Oct 2008 04:13:50 +0000 From: Bruce Cran <bruce@cran.org.uk> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-net@freebsd.org Subject: Re: two NIC on 2 core system (scheduling problem) Message-ID: <20081031041350.4e25edc7@tau.draftnet> In-Reply-To: <ge6sia$6as$1@ger.gmane.org> References: <200810281235.53508.gizmen@blurp.pl> <4906EC8D.7070503@freebsd.org> <4906EE31.3080400@samoylyk.sumy.ua> <ge6sia$6as$1@ger.gmane.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 28 Oct 2008 12:21:32 +0100 Ivan Voras <ivoras@freebsd.org> wrote: > Oleksandr Samoylyk wrote: > > Ivan Voras wrote: > >> Bartosz Giza wrote: > >> > >>> Another question is why em0 taskq is eating so much cpu ? BGE > >>> interface is actually one that pushes 2 times more packets than > >>> em0 and it uses about half cpu comparing to em0. Is that not > >>> strange ? Could someone tell my why is this happening ? BGE is > >>> faster ? or maybe i can tune some > >> > >> I have the same problem - em0 taskq eating incredible amounts of > >> CPU. If you find a solution, contact me! > >> > >> > >=20 > > It could be not just a problem with em driver. > > Firstly, it's good to make profiling and find out what exactly eats > > CPU >=20 > Can you give any pointers on how to profile the driver and/or the > network stack? >=20 =46rom what I remember from a couple of years ago you can use hwpmc in system mode to profile the kernel if you have a supported CPU - I certainly remember seeing the output of gprof tell me the UDP checksum function was taking most of the time in a test I ran. To get started you need options HWPMC_HOOKS and device hwpmc in your kernel config (hwpmc can also be a module) - then you run pmcstat to run the test. There's lots more information at http://wiki.freebsd.org/PmcTools --=20 Bruce Cran
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20081031041350.4e25edc7>