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I've been sitting on these patches for > over a year, and Jonathan Lemon had a similar series years before. > We never deployed it or sent upstream because it didn't really show > much perf win under normal load (admittedly I think the real testing > was done before Ilias's work on recycling). > > During the v6.9 kernel rollout Meta's CDN team noticed that machines > with CX3 Pro (mlx4) are prone to overloads (double digit % of CPU time > spent mapping buffers in the IOMMU). The problem does not occur with > modern NICs, so I dusted off this series and reportedly it still works. > And it makes the problem go away, no overloads, perf back in line with > older kernels. Something must have changed in IOMMU code, I guess. > > This series is very simple, and can very likely be optimized further. > Thing is, I don't have access to any CX3 Pro NICs. They only exist > in CDN locations which haven't had a HW refresh for a while. So I can > say this series survives a week under traffic w/ XDP enabled, but > my ability to iterate and improve is a bit limited. Hi Jakub, Thanks for your patches. As this series touches critical data-path area, and you had no real option of testing it, we are taking it through a regression cycle, in parallel to the code review. We should have results early next week. We'll update. Regards, Tariq > > Jakub Kicinski (4): > eth: mlx4: create a page pool for Rx > eth: mlx4: don't try to complete XDP frames in netpoll > eth: mlx4: remove the local XDP fast-recycling ring > eth: mlx4: use the page pool for Rx buffers > > drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 15 +-- > drivers/net/ethernet/mellanox/mlx4/en_rx.c | 120 +++++++------------ > drivers/net/ethernet/mellanox/mlx4/en_tx.c | 17 ++- > 3 files changed, 53 insertions(+), 99 deletions(-) >