On 06/17, David Marchand wrote: >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).
Sounds better, will try. Thanks, Xiaolong > > >-- >David Marchand
