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List:       netbsd-tech-kern
Subject:    Re: NetBSD + PCI: questions & concerns
From:       Pavel Cahyna <pavel () NetBSD ! org>
Date:       2007-01-29 9:38:55
Message-ID: 20070129093855.GA1205 () beta ! martani ! repy ! czf
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On Sun, Jan 28, 2007 at 02:55:20AM -0600, David Young wrote:
> I have been reading[1] about PCI, and experimenting under NetBSD.
> I have a couple of questions/concerns:
> 
> 1 PCI Latency Timer (LT)
> 
>   Here is a braindump that I will have to unpack later: x86 BIOS
>   ordinarily programs LT without regard for device requirements, and
>   NetBSD just leaves the BIOS' LT settings on x86.  Performance may
>   suffer because of it.  I believe NetBSD can do better.  Programming the
>   LT on PCI-PCI and PCI-Cardbus bridges may deserve special attention.
>   Fiddling with LT helped rtw avoid Tx FIFO underruns.

Indeed. See http://article.gmane.org/gmane.os.netbsd.devel.kernel/13106
("Should Alpha PCI code manage latency timers?")
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