On Sat, 2004-01-24 at 15:04, Leonid Grossman wrote:
> These schemes could be complimentary, right now we do see that different
> thresholds need to be programmed for regular and Jumbo traffic.
> One thing I did not mention is that our ASIC supports several
> utilization thresholds on per interrupt basis (up to 64 MSI-X
> interrupts). There are also independent tx and rx queues, and each can
> have it's own interrupt. There is a pretty large number of parameters
> that traffic could be steered upon, packet size is one of them.
Would be interesting to see what these queue selection parameters are.
For example, an extremely important thing to avoid is reordering of
packets. You reorder packets on a TCP flow and you perfomance goes
> So, if you want to have different interrupt moderation schemes for
> different packet sizes, you just need to steer packets to separate
> queues based upon size, and then assign a separate MSI interrupt to
> these queues and set different utilization thresholds for different
> interrupts. At any given workload, you will be getting interrupts at
> different rate for small and for big packets.
Does sound interesting, but i am suspcious about reordering; i.e you
dont want a 64 byte packet from one flow to be in a different queue
than another which is 1500 bytes. The 2 packet must be processed
strictly in FIFO manner.
> Anyway, you are right there are many interrupt moderation schemes that
> host driver can deploy, our goal was to provide a flexible hardware
So is it possible to program it such that if a threshold interupt rate
is crossed it adjusts its mitigation values? actually i should say its
the second order effect that is of interest to the threshold i.e the
integral of the interupt arrival rate.