On 9/17/20 2:23 PM, Jesse Brandeburg wrote: > Nitesh Narayan Lal wrote: > >> In a realtime environment, it is essential to isolate unwanted IRQs from >> isolated CPUs to prevent latency overheads. Creating MSIX vectors only >> based on the online CPUs could lead to a potential issue on an RT setup >> that has several isolated CPUs but a very few housekeeping CPUs. This is >> because in these kinds of setups an attempt to move the IRQs to the >> limited housekeeping CPUs from isolated CPUs might fail due to the per >> CPU vector limit. This could eventually result in latency spikes because >> of the IRQ threads that we fail to move from isolated CPUs. >> >> This patch prevents i40e to add vectors only based on available >> housekeeping CPUs by using num_housekeeping_cpus(). >> >> Signed-off-by: Nitesh Narayan Lal <nitesh@xxxxxxxxxx> > The driver changes are straightforward, but this isn't the only driver > with this issue, right? Indeed, I was hoping to modify them over the time with some testing. > I'm sure ixgbe and ice both have this problem > too, you should fix them as well, at a minimum, and probably other > vendors drivers: Sure, I can atleast include ixgbe and ice in the next posting if that makes sense. The reason I skipped them is that I was not very sure about the right way to test these changes. > > $ rg -c --stats num_online_cpus drivers/net/ethernet > ... > 50 files contained matches > > for this patch i40e > Acked-by: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx> > -- Thanks Nitesh
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