Date: Thu, 19 Jun 1997 16:20:15 -0700 From: David Greenman <dg@root.com> To: Chris Csanady <ccsanady@friley01.res.iastate.edu> Cc: sthaug@nethelp.no, hackers@FreeBSD.ORG Subject: Re: Network concurrency problems!? Message-ID: <199706192320.QAA07656@implode.root.com> In-Reply-To: Your message of "Thu, 19 Jun 1997 18:08:44 CDT." <199706192308.SAA13293@friley01.res.iastate.edu>
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>BTW, does the intel card use DBDMA? From the driver, it looks like >something similar. How about the dec? What is DBDMA? >Also, this is sortof an aside, but I am writing a new driver, and was >wondering about using mem mapped vs io mapped registers. How much of >a difference in performance is there? Or should I just do a lot of outl()'s? >(like in linux.. but its really ugly imho..) > >The memory/PCI busses are already a significant bottleneck, so I dont think >I can afford to sacrifice too much.. Programmed I/O instruction on the P6 (and Pentium II) are serialized in a way that makes them extremely expensive; memory mapped PCI operations are much faster because of this. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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