From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Hutchings <bhutchings@solarflare.com>
Subject: Re: why all packets have same queue no when rps enabled?
Date: Tue, 22 Feb 2011 13:09:25 +0000
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Cc: Jon Zhou <Jon.Zhou@jdsu.com>,
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To: Eric Dumazet <eric.dumazet@gmail.com>
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On Tue, 2011-02-22 at 14:01 +0100, Eric Dumazet wrote:
> Le mardi 22 f=C3=A9vrier 2011 =C3=A0 12:45 +0000, Ben Hutchings a =C3=
=A9crit :
>=20
> > The queue number identifies a hardware queue.  RPS therefore does n=
ot
> > update this number when queueing packets for processing on other CP=
Us.
> >=20
> > If the hardware/driver provides a receive hash (probably Toeplitz) =
then
> > this is used for RPS.  Otherwise a much cheaper hash is used.
>=20
> The default is/should be : rxhash generated in network stack.
>=20
> ethtool -k eth0 | grep hash
> receive-hashing: off
>=20
> To use the device/harwdare provided rxhash, you need to ask for it.
>=20
> ethtool -K eth0 rxhash on

Whether this is enabled by default depends on the driver.

> BTW, I am not sure what you mean by "much cheaper hash is used"...
>=20
> I presume hardware provided hash is less expensive (for our cpu) than
> computing our rxhash...

I mean the hash function we use is much cheaper than Toeplitz.

Ben.

--=20
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.