Re: Info: NAPI performance at "low" loads

From: David S. Miller (davem@redhat.com)
Date: Wed Sep 18 2002 - 15:23:34 EST


   From: ebiederm@xmission.com (Eric W. Biederman)
   Date: 18 Sep 2002 11:27:34 -0600

   "David S. Miller" <davem@redhat.com> writes:
   
> {in,out}{b,w,l}() operations have a fixed timing, therefore his
> results doesn't sound that far off.
   ????
   
   I don't see why they should be. If it is a pci device the cost should
   the same as a pci memory I/O. The bus packets are the same. So things like
   increasing the pci bus speed should make it take less time.

The x86 processor has a well defined timing for executing inb
etc. instructions, the timing is fixed and is independant of the
speed of the PCI bus the device is on.
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