Re: CPU affinity with ULE scheduler

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--