Subject: Re: NetBSD + PCI: questions & concerns
To: None <tech-kern@netbsd.org>
From: Pavel Cahyna <pavel@netbsd.org>
List: tech-kern
Date: 01/29/2007 10:38:55
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?")