[rt2x00-users] [RFC/RFT] rt2x00: Fix PCI irq processing race on SMP systems

[Helmut Schaa]

Am Montag, 25. Juli 2011 schrieb Andreas Hartmann:
> Helmut Schaa schrieb:
> > Am Sonntag, 24. Juli 2011 schrieb Andreas Hartmann:
> >> Helmut Schaa schrieb:
> >>> Am Donnerstag, 21. Juli 2011 schrieb Andreas Hartmann:
> >>>> Helmut Schaa schrieb:
> >>>>> Am Donnerstag, 21. Juli 2011 schrieb Andreas Hartmann:
> >>>>>> Sorry, but I have to disappoint you - the warning message came up as
> >>>>>> before :-(. I tested two times, in between the unpatched compat-wireless
> >>>>>> - always the same result (here one example):
> >>>>>
> >>>>> Ok, thanks for trying anyway. I'm pretty sure I asked before but do you run
> >>>>> 40Mhz or 20Mhz?
> >>>>
> >>>> 40MHz! I want to have power :-)!
> >>>
> >>> Oh, Andreas could you please check if reducing the queue limit to 8 as in the
> >>> rt2x00 USB RFC I sent before makes any difference?
> >>
> >> Ok, besides the crash mentioned in another mail, I couldn't see any more
> >> crash. Don't know, why this happened.
> >>
> >> Now to the throughput between the queue limit 8 or 64. I played around
> >> very long, changed forth and back between 8 and 64 - but to be honest, I
> >> couldn't get any preference for the one or the other.
> > 
> > Sorry, I wasn't clear on this. I was thinking if using a queue len of 8 would
> > cause the queue flush problems to disappear?
> 
> Well, besides the described impact at the other mail, I couldn't see any
> Warnings on ending hostapd - but they didn't come up with 64, too (as
> long as X was off).
> 
> I couldn't see a warning too in the case, where X was running and the
> queue limit was 8 (where I got the dropping frame errors before). If
> this could be representative, I can't say, because the warnings don't
> come up on every end of hostapd and queue limit 64 w/ X.
> 
> 
> BTW: There is no interrupt sharing between X and the WLAN-card:
> 
> X runs with IRQ 18, WLAN-card with 21. There is no other device running
> with IRQ 21.
> 
> 
> I'm thinking of doing some more tests with reduced queue limit and w/ X,
> but to be honest, I fear the hard crashes which could destroy my
> filesystems with irreparable damage and data loss at the end. I recently
> had to reinstall a machine two times because of hard locks and
> afterwards totally broken ext4 filesystem. So, if you really need a
> resilient statement, I would have to think about to reduce the potential
> damage of the filesystems.

Nah, that's ok. I just ordered a rt2800 pccard for use in my SMP laptop. So,
I might be able to do some tests myself soon.

Helmut