On Mon, Jun 17, 2019 at 10:45 AM Ye Xiaolong <xiaolong...@intel.com> wrote:
> On 06/17, David Marchand wrote: > >On Mon, Jun 17, 2019 at 9:42 AM Xiaolong Ye <xiaolong...@intel.com> > wrote: > > > >> This patch adds a new devarg to support the need_wakeup flag for Tx and > >> fill rings, when this flag is set by the driver, it means that the > >> userspace application has to explicitly wake up the kernel Rx or kernel > Tx > >> processing by issuing a syscall. Poll() can wake up both and sendto() or > >> its alternatives will wake up Tx processing only. > >> > >> This feature is to provide efficient support for case that application > and > >> driver are executing on the same core. > >> > >> Signed-off-by: Xiaolong Ye <xiaolong...@intel.com> > >> --- > >> > >> Original busy poll feature has morphed into need_wakeup flag in > >> kernel side, the main purpose is the same, that is to support both > >> application and driver executing on the same core efficiently. > >> > >> kernel side patchset can be found at netdev mailing list. > >> > >> > https://lore.kernel.org/netdev/CAJ8uoz2szX=+jxxamyuvmvssmxzudqp6a8rjdqptioxbzwx...@mail.gmail.com/T/#t > >> > >> It is targeted for v5.3 > >> > > > >- Is this really optional? Adding too many options is just a nightmare > >later... > > Hmm, I think we can remove this option and alway turn the need_wakeup flag > on > since it provides better performance for 1 core case and doesn't downgrage > the > 2 core case performance. > > > > >- I suppose this will break compilation with kernels that have af_xdp but > >are < 5.3. > > Yes, that is true. It will break the compilation with early kernel, I feel > it's > sort of common issue, we enable some features in dpdk that's based on > kernel > features, then kernel side features keep evolving, we need to keep the > pace, > but it will hurt the compatiblity with the old kernel. > > What's dpdk's convention for handling this kind of case? Add some notes in > doc > to reminder the prerequisite or use the KERNEL_VERSION macro in code? > Rather than a kernel version, you can check that XDP_USE_NEED_WAKEUP is defined (present in the uapi kernel header). -- David Marchand
