On Thu, 2005-03-31 at 17:42, Rick Jones wrote:
> I "never" see that because I always bind a NIC to a specific CPU :) Just
> every networking-intensive benchmark report I've seen has done the same.
Do you have to be so clever? ;->
> > Note Linux is quiet resilient to reordering compared to other OSes (as
> > you may know) but avoiding this is a better approach - hence my
> > suggestion to use NAPI when you want to do serious TCP.
> Would the same apply to NIC->CPU interrupt assignments? That is, bind the NIC
> a single CPU.
No reordering there.
> > Dont think we can do that unfortunately: We are screwed by the APIC
> > architecture on x86.
> The IPS and TOPS stuff was/is post-NIC-interrupt. Low-level driver processing
> still happened/s on a specific CPU, it is the higher-level processing which
> done on another CPU. The idea - with TOPS at least, is to try to access the
> (TCP, UDP etc) structures on the same CPU as last accessed by the app to
> minimize that cache to cache migration.
But if interupt happens on "wrong" cpu - and you decide higher level
processing is to be done on the "right" cpu (i assume queueing on some
per CPU queue); then isnt that expensive? Perhaps IPIs involved even?