Date: Tue, 11 Mar 1997 10:23:48 -0500 From: dennis <dennis@etinc.com> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: hackers@freebsd.org Subject: Re: performance (was: 100 Mb/s cards) Message-ID: <3.0.32.19970311102342.00b05710@etinc.com>
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At 11:55 AM 3/11/97 +1030, you wrote: >David Greenman stands accused of saying: >> Regarding the difference in performance between the de and fxp drivers, >> all I can say to this is that the code paths in the de driver are long and >> complicated. It's entirely likely that they have to be this way for whatever >> reason (I've not looked into improving it). The time reduction I measured with >> the fxp driver was primarily %interrupt, but there is a reduction in system >> time as well (too difficult to measure accuraterly on wcarchive, but perhaps >> 5-10%). > >There is also a comment in the de driver that implies that the packets >that come in from the card are wrongly aligned (in some fashion) and >have to be copied anyway, which may account for the overhead. The comment implies that there is something "stupid" about the controllers quad alignment requirement, but whoever wrote that should know that all PCI bus master accesses MUST be quad aligned as a basic requirement of the spec. Dennis
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