On Tuesday, 12 June 2007 23:56, Siddha, Suresh B wrote: > On Tue, Jun 12, 2007 at 10:52:09PM +0200, Rafael J. Wysocki wrote: > > On Tuesday, 12 June 2007 20:19, Eric W. Biederman wrote: > > > Because you are calling unfixably broken code. That should be a decent > > > incentive to do something else won't it? > > > > Can you please tell me _what_ else can be done? > > > > > IOAPICs do not support what the code is doing here. There is lots of > > > practical evidence including bad experiences and practical tests that > > > support this. > > > > Well, AFAICS, Suresh has tried to debug one failing case recently without > > any consistent conclusions. I don't know of any other test cases (links, > > please?). > > Rafael, Darrick Wong's issue looks different and hence I was motivated to > look and fix if it was a SW issue. For now, I am not able to comprehend > what is happening on Darrick Wong's system. Need more help from Darrick > as he has the golden failing system. > > Meanwhile I talked to our hardware folks about the irq migration in general. > > One good news is that future versions of chipsets will have an Interrupt > Remapping feature(for more details please refer to > http://download.intel.com/technology/computing/vptech/Intel(r)_VT_for_Direct_IO.pdf) > where in we can reliably migrate the irq to someother cpu in the process > context. > > And for the existing platforms, chipset folks don't see a reason why the > Eric's algorithm(specified below) should fail. > > Eric's algorithm for level triggered(edge triggered should be easier than > level triggered): > - Mask the irq in process context. > - Poll RIRR until an ack of for the irq was not pending. > - Migrate the irq. > > Eric had a problem of stuck remote IRR on E75xx chipset with this algorithm > and my next step is to reproduce this issue on this platform and understand > the behavior.
OK In that case, do I understand correctly that we are going to implement the Eric's algorithm above for the CPU hotunplugging on x86 once you've figured out what's the E75xx issue? Rafael -- "Premature optimization is the root of all evil." - Donald Knuth - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
