Date: Thu, 1 Nov 2007 11:21:15 -0400 From: John Baldwin <jhb@freebsd.org> To: "Jack Vogel" <jfvogel@gmail.com> Cc: freebsd-current@freebsd.org, Mike Tancsa <mike@sentex.net> Subject: Re: em0: watchdog timeout ... Message-ID: <200711011121.15687.jhb@freebsd.org> In-Reply-To: <2a41acea0710311544x5db98f27ta0f1276fd06d13f@mail.gmail.com> References: <20071011003619.GA84433@obelix.dsto.defence.gov.au> <200710312232.l9VMWgJJ090112@lava.sentex.ca> <2a41acea0710311544x5db98f27ta0f1276fd06d13f@mail.gmail.com>
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On Wednesday 31 October 2007 06:44:36 pm Jack Vogel wrote: > On 10/31/07, Mike Tancsa <mike@sentex.net> wrote: > > At 06:25 PM 10/31/2007, Jack Vogel wrote: > > > > > > > > > >What if you use MSI? > > > > > > > > How do I enable that ? > > > > > >sysctl hw.pci.enable_msi=1 > > > > > >and > > > > > >sysctl hw.pci.enable_msix=1 > > > > > >For those that don't know, MSI/X is there in STABLE but off by default. > > > > Thanks, > > Do I need to do this in /boot/loader.conf or can I set it at > > any time? Are there any performance hits / boosts to use this method > > instead of the default ? > > I have set it after the system booted and it seemed to work. > > John could speak more authoritatively since he wrote it, but I have > seen no problem turning em use on whenever. Uh, this means of > course, enabling it and THEN loading the driver, if em is loaded and > you enable the system it will have no effect on em until unload and > reloading it. > > John has also said that MSI in 6.X is not as full an implementation as > in 7 but I don't recall what that amounted to. > > It means you have a unique unshared interrupt, I have never really had > any performance tests done on MSI vs Legacy so I can't speak to that. The only thing MSI in 6.x doesn't have is the MSI-X remap function, the rest of the implementation is identical. I just haven't enabled it by default on 6.x due to caution. -- John Baldwin
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