* Mikael <mikael.tr...@gmail.com> [2014-10-14 16:35]: > 2014-10-14 16:15 GMT+02:00 Henning Brauer <hb-open...@ml.bsws.de>: > > > i.e. there's no way for a userland application to do high speed > > > packet-level IO. > > there are plenty of methods actually. > Like what?
bpf, for example. but since you still don't mention what problem you're trying to solve... > > userland reimplementing the stack[...] > I didn't necessarily/specifically suggest that. but that's what you effectively HAVE TO DO with netmap, unless you're creating some layer2 bridge (which belongs in kernel space), or just want to listen (there is bpf for that). > > There is a whole world of need of network monitoring and manipulation and > > > other specialized networking software. > > > > I read a collection of buzzwords with nothing specific. > > > > "A solution in dire need of a problem." > Will be more clear on this one following your response. Last for completing > reflections - > > Most devices in a system can be accessed with good performance from > userland as it is now, for instance block devices, USB, serial ports, video > and audio. > > Ethernet is a rare exception and NetMap solved this in a neat way - bolloks. foremost, in almost all cases you don't speak ethernet, you speak IP (just like you don't speak USB to access a umass in userland). > Prior to NetMap, those who wanted to make high-performance ethernet IO in > userland would run their app as root and effectively implement NIC hardware > drivers in userland. NetMap generalized this entire problem to one > hardware-agnostic interface. ok, still bla bla without a use case, not even speaking about a valid one or one that is common enough to push yet another network subsystem into the kernel. still stinks like a solution in need of a problem. netmap is luigi's research framework, and he used it for some cool research an sure will do so more in the future. no more, no less. All this stack bypassing and (partial and buggy) reimplementation in userland baloony has to stop. Introducing interop and security issues just to look a little better in made up microbenchmarks, without any real world relevance, what an awesome deal. The time needed to "port" netmap (which includes touching EVERY NIC driver) plus the time for the fruitless attempt to get IP processing close to right in userland to make a specific application a little faster is spent much better improving the network stack itself - for all applications. -- Henning Brauer, h...@bsws.de, henn...@openbsd.org BS Web Services GmbH, http://bsws.de, Full-Service ISP Secure Hosting, Mail and DNS. Virtual & Dedicated Servers, Root to Fully Managed Henning Brauer Consulting, http://henningbrauer.com/
