[ATA] and re(4) stability issues

[Pyun YongHyeon]

On Wed, Dec 10, 2008 at 03:08:24PM +0100, Victor Balada Diaz wrote:
 > On Wed, Dec 10, 2008 at 09:07:19PM +0900, Pyun YongHyeon wrote:

[...]

 > >  > >  > > It seems that your controller supports MSI so you can set a tunable
 > >  > >  > > hw.re.msi_disable to 0 to enable MSI. With MSI you can remove
 > >  > >  > > interrupt sharing(e.g. add hw.re.msi_disable="0" to
 > >  > >  > > /boot/loader.conf file.) However there were several issues on re(4)
 > >  > >  > > w.r.t MSI so it was off by default.
 > >  > >  > 
 > >  > >  > This is undocumented and with sysctl -a i can't find the tunable. Is this
 > >  > >  > a HEAD feature or it's also in 7.1 -BETA2? Should i add
 > >  > > 
 > >  > > Yeah it's an undocmented feature. But most drivers written by me
 > >  > > have similar kobs. Both HEAD and stable/7 including 7.1 BETA2 have
 > >  > > the tunable.
 > >  > 
 > >  > I think it could be great if you could document it or at least
 > >  > show it by default when you do sysctl -ad with a small description.
 > >  > 
 > > 
 > > If MSI worked as expected I would have documented it as I did
 > > in msk(4)/nfe(4)/ale(4)/age(4)/jme(4) etc.
 > > Using MSI on RealTek does not seem to stable. I tried hard to fix
 > > that but some users still reported watchdog timeouts. Working
 > > without documentation and hardware also made it hard to complete
 > > the work. This was the main reason why MSI was disabled on re(4).
 > 
 > What do you think about adding a note in the man page telling that
 > it's experimental and in some cases it could improve the situation
 > but in others it will give errors? 

Based on the your testing I have idea how to mitigate the missing
Tx completion interrupt. If all goes well re(4) could reliably take
advantage of MSI on RealTek controllers. If that miserably fail I
would do as you suggested.

 > > 
 > > I think re(4) in HEAD needs more testing. As you might know RealTek
 > > produced too many chipsets. :-(
 > 
 > Ok, i'll use the backported driver as it works better for me :-)
 > 
 > If i can help you testing any patches i'm more than welcome to do it.
 > 
 > Thanks a lot for your help Pyun YongHyeon.
 > 

You're welcome.
-- 
Regards,
Pyun YongHyeon