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Date: Mon, 21 Apr 2003 17:35:59 -0600 (MDT)
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To: rizzo@icir.org
From: "M. Warner Losh" <imp@bsdimp.com>
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cc: freebsd-hackers@freebsd.org
Subject: Re: wi(4) - polling(4) changes / DEVICE_POLLING
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In message: <20030421064717.B98117@xorpc.icir.org>
            Luigi Rizzo <rizzo@icir.org> writes:
: if i remember well, the "wi" driver copies the packet from the card
: to the mbuf using programmed I/O. Switching to polling will just
: move the load under a different bucket (SYSTEM or IDLE instead
: of INTR) but not change the situation radically, and i
: doubt you will achieve significant performance improvements.

The wi driver does use PIO to move the data from the cards to memory.
Newer PCI and mini-pci cards support using DMA to do this, but there's
no support for that in the driver at the moment.

The wi cards are just damn expensive to talk to :-(.

Warner