Fiasco.OC performance issues

Adam Lackorzynski adam at
Thu Jan 17 23:31:12 CET 2013

On Thu Jan 17, 2013 at 17:03:36 +0100, Sebastian Sumpf wrote:
> I recently upgraded Fiasco.OC to SVN revision 42 and experience some
> pretty severe performance degradation compared to revision 40 on the
> Pandaboard (SMP). It seems that 'simga0' and the root task stall for 5
> to 10 seconds during boot up. I tracked the issue down to be caused by
> the initial mapping operations, especially our root task maps all the
> available memory during bootstrap. Within the kernel the
> 'Context::xcpu_tlb_flush' is called for each mapping. The function sends
> an IPI (to CPU1 which is idle) and then waits for an IPI in order to
> signal the end of the operation. The whole operation seems to have
> gotten slower compared to revision 40, but I could not find many
> differences in the IPI-handling code. Do you have any ideas or
> suggestions what could cause the delay (maybe scheduling changes) and
> how to fix it?

I noticed a similar/same thing but hadn't time to investigate yet.

Adam                 adam at

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