Re: em0: watchdog timeout ...

On Wednesday 31 October 2007 06:44:36 pm Jack Vogel wrote:
> On 10/31/07, Mike Tancsa <mike_at_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