Messages in this thread | | | Date | Sat, 20 Nov 2004 15:29:29 +1100 | From | Nick Piggin <> | Subject | Re: page fault scalability patch V11 [0/7]: overview |
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William Lee Irwin III wrote: > William Lee Irwin III wrote: > >>>/proc/ triggering NMI oopses was a persistent problem even before that >>>code was merged. I've not bothered testing it as it at best aggravates it. > > > On Sat, Nov 20, 2004 at 03:03:17PM +1100, Nick Piggin wrote: > >>It isn't a problem. If it ever became a problem then we can just >>touch the nmi oopser in the loop. > > > Very, very wrong. The tasklist scans hold the read side of the lock > and aren't even what's running with interrupts off. The contenders > on the write side are what the NMI oopser oopses. >
*blinks*
So explain how this is "very very wrong", then?
> And supposing the arch reenables interrupts in the write side's > spinloop, you just get a box that silently goes out of service for > extended periods of time, breaking cluster membership and more. The > NMI oopser is just the report of the problem, not the problem itself. > It's not a false report. The box is dead for > 5s at a time. >
The point is, adding a for-each-thread loop or two in /proc isn't going to cause a problem that isn't already there.
If you had zero for-each-thread loops then you might have a valid complaint. Seeing as you have more than zero, with slim chances of reducing that number, then there is no valid complaint.
> > William Lee Irwin III wrote: > >>>And thread groups can share mm's. do_for_each_thread() won't suffice. > > > On Sat, Nov 20, 2004 at 03:03:17PM +1100, Nick Piggin wrote: > >>I think it will be just fine. > > > And that makes it wrong on both counts. The above fails any time > LD_ASSUME_KERNEL=2.4 is used, we well as when actual Linux features > are used directly. >
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