hhmm.. In the driver i am using, the secret key is fixed, its a constant 40
byte value.

In the RSS,  after the hashing, rss looks at one indirection table (using
the hash value obtained from the hashing algo) which has the index of the
CPUs. Whichever the index that hash result in, that particular CPU (or
queue) is selected. I am not sure, but i think this indirection table gets
changed as a result of which the queue assignment changes. But i am not sure
its done by the driver or whether the indirection table gets changed
whenever reboot happens or it changes based upon the load on the
queues. Please throw some light on this.



On Mon, Jun 1, 2009 at 10:53 AM, Brandeburg, Jesse <
jesse.brandeb...@intel.com> wrote:

>
>
> On Mon, 1 Jun 2009, vikram wrote:
> > I found this peculiar thing regarding the hashing in RSS. According to
> the
> > hashing algorithm, for a particular source and destination ip address and
> > port numbers, the packets should be always hashed to the same queue since
> > the hashing algorithm uses only a fixed secret key in addition to the
> source
> > and dest ip and port numbers for hashing. But what happens is, when i
> reboot
> > the machine, the queue assignment changes. Just wanted to know whether
> the
> > hashing takes anything in consideration in addition to the above
> mentioned
> > parameters?
>
> If the driver you're using has a get_random_bytes feeding the secret key
> (as some of our older drivers did) then you'll see the "random" queue
> selection after each reboot.
>
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