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Date:      Tue, 2 Apr 2002 13:39:17 -0800 (PST)
From:      Stefan Saroiu <tzoompy@cs.washington.edu>
To:        freebsd-smp@FreeBSD.org
Subject:   Interrupt Handlers and Multiple CPUs
Message-ID:  <20020402132930.B28718-100000@magnesium.cs.washington.edu>

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Hello,

This is the context.

I am writing a packet capture application on a PIV 2GHz single proc 
machine with a SK-9843 1Gbps network card. Under 6-700 Mbps of traffic, 
60-70% of the CPU is spent inside of the interrupt handler. This 
is the interrupt coming from the NIC (pci/if_sk.c). 

Because so many CPU cycles are spent on these interrupts, the packet 
capture application gets starved over time. 

Now the question:
================

If I drop a second CPU in the box, will FreeBSD be smart to schedule the 
interrupts on one CPU and the packet capture code on the other? What 
FreeBSD version do I need (I have 4.5)?

The SMP docs on the FreeBSD site seem to point to an affirmative answer, 
but I'd like to get more opinions before I blow more money on a second 
CPU. 

Many thanks,
--Stefan




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