Date: Mon, 17 Nov 2008 14:18:36 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-smp@freebsd.org Subject: Re: CPU affinity with ULE scheduler Message-ID: <gfrqtv$ole$1@ger.gmane.org> In-Reply-To: <42e3d810811170311uddc77daj176bc285722a0c8@mail.gmail.com> References: <42e3d810811100033w172e90dbl209ecbab640cc24f@mail.gmail.com> <200811111216.37462.jhb@freebsd.org> <42e3d810811130355x3857bceap447e134b18eee04b@mail.gmail.com> <200811131128.55220.jhb@freebsd.org> <42e3d810811170311uddc77daj176bc285722a0c8@mail.gmail.com>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig72EB5AC1004F9F67F4407EC7 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Archimedes Gaviola wrote: > With net.isr.direct=3D0, my IBM system lessens CPU utilization per > interface (bce0 and bce1) but swi1:net increase its utilization. > Can you explained what's happening here? What does net.isr.direct do > with the decrease of CPU utilization on its interface?=20 The system has a choice between processing the packets in the interrupt handler (the "irq:bce" process) or in a dedicated network process (the "swi:net" process). This is about protocol handling not simply receiving packets. With net.isr.direct you're toggling between those two options. If "direct" is 1, the packets are processed in the interrupt handler; if it's 0, the processing is delegated to swi. It's set to 1 by default because this setting should yield best latency. In both cases the code path a packet must go through is very similar: it has to be received, then processed through firewalls and network stack code, then delivered to application(s), so it's a serial process. There are things that could be better parallelized in the stack and people are working on them, but they will not be finished any time soon. --------------enig72EB5AC1004F9F67F4407EC7 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFJIW8sldnAQVacBcgRAnPQAKC+5qlyAtI+mTT5eFP4te2BX8EWXgCg+REw Ff9Lv7GNlBhrtGNsp9Ojkss= =0AJK -----END PGP SIGNATURE----- --------------enig72EB5AC1004F9F67F4407EC7--
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