Sami Tolvanen <samitolvanen@xxxxxxxxxx> writes: > On Wed, Sep 11, 2019 at 5:09 AM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: >> >> Björn Töpel <bjorn.topel@xxxxxxxxx> writes: >> > I ran the "xdp_rxq_info" sample with and without Sami's patch: >> >> Thanks for doing this! > > Yes, thanks for testing this Björn! > >> Or (1/22998700 - 1/23923874) * 10**9 == 1.7 nanoseconds of overhead. >> >> I guess that is not *too* bad; but it's still chipping away at >> performance; anything we could do to lower the overhead? > > The check is already rather minimal, but I could move this to a static > inline function to help ensure the compiler doesn't generate an > additional function call for this. I'm also fine with gating this > behind a separate config option, but I'm not sure if that's worth it. > Any thoughts? I think it would be good if you do both. I'm a bit worried that XDP performance will end up in a "death by a thousand paper cuts" situation, so I'd rather push back on even relatively small overheads like this; so being able to turn it off in the config would be good. Can you share more details about what the "future CFI checking" is likely to look like? -Toke
