Date: Fri, 9 Sep 2011 01:53:10 +0000 From: Navdeep Parhar <np@FreeBSD.org> To: Ben Hutchings <bhutchings@solarflare.com>, rwatson@FreeBSD.org Cc: jfv@freebsd.org, freebsd-net@freebsd.org, John Baldwin <jhb@freebsd.org>, Takuya ASADA <syuu@dokukino.com> Subject: Re: Adding Flow Director sysctls to ixgbe(4) Message-ID: <20110909015310.GB24670@hub.freebsd.org> In-Reply-To: <1315529074.2804.63.camel@bwh-desktop> References: <CALG4x-W99OZxd=1ZDvW4=MBqeE3RPOazc7jc_3O30X-Pou3k8Q@mail.gmail.com> <1315221674.3092.282.camel@deadeye> <201109080834.11607.jhb@freebsd.org> <20110908184928.GA87872@hub.freebsd.org> <37419C45-4436-4738-851B-2B765BC2C60F@neville-neil.com> <1315529074.2804.63.camel@bwh-desktop>
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On Fri, Sep 09, 2011 at 01:44:34AM +0100, Ben Hutchings wrote: > On Thu, 2011-09-08 at 20:13 -0400, George Neville-Neil wrote: > > On Sep 8, 2011, at 14:49 , Navdeep Parhar wrote: > > > > > On Thu, Sep 08, 2011 at 08:34:11AM -0400, John Baldwin wrote: > > >> On Monday, September 05, 2011 7:21:12 am Ben Hutchings wrote: > > >>> On Mon, 2011-09-05 at 15:51 +0900, Takuya ASADA wrote: > > >>>> Hi, > > >>>> > > >>>> I implemented Ethernet Flow Director sysctls to ixgbe(4), here's a detail: > > >>>> > > >>>> - Adding removing signature filter > > >>>> On linux version of ixgbe driver, it has ability to set/remove perfect > > >>>> filter from userland using ethtool command. > > >>>> I implemented similar feature, but on sysctl, and not perfect filter > > >>>> but signature filter(which means hash collision may occurs). > > >>> [...] > > >>> > > >>> Linux also has a generic interface to RX filtering and hashing > > >>> (ethtool_rxnfc) which ixgbe supports; wouldn't it be better for FreeBSD > > >>> to support something like that? > > >> > > >> Some sort of shared interface might be nice. The cxgb(4) and cxgbe(4) drivers > > >> both provide their own tools to manipulate filters, though they do not > > >> provide explicit steering IIRC. > > > > > > Both of them can filter as well as steer (and the tools let you do that). > > > cxgbe(4) can do a lot more (rewrite + switch, replicate, etc.) but those > > > features are perhaps too specialized to be configurable via a general > > > purpose tool. > > > > > >> > > >> We would need to come up with some sort of standard interface (ioctls?) for > > >> adding filters however. > > > > > > +1 for a standard interface. > > > > > > imho the kernel needs to be aware of the rx and tx queues of a NIC, and > > > not just for steering. But that's a separate discussion. > > > > > > > Well I do think this is actually all of a part. Most of us realize by now that > > high speed (e.g. 10G and higher) NICs only make sense if you can steer traffic and > > pin queues to cores etc. > > Well, you can get way better than 1G performance without that. And for > routers, flow hashing may be fine. But for a host, of course, steering > packets properly can provide a major performance win. > > [...] > > What this means is that we have > > a failure of abstraction. Abstraction has a cost, and some of the people who want > > access to low level queues are not interested in paying an extra abstraction cost. > > Abstraction has a cost, but it's not necessarily that high compared to > rewriting a whole chunk of sockets code (especially if you don't > actually have the source code). > > > I think that some of the abstractions we need are tied up in the work that Takuya did > > for SoC and some of it is in the work done by Luigi on netmap. I'd go so far as to say > > that what we should do is try to combine those two pieces of code into a set of > > low level APIs for programs to interact with high speed NICs. The one thing most > > people do not talk about is extending our socket API to do two things that I think would > > be a win for 80% of our users. If a socket, and also a kqueue, could be pinned > > to a CPU as well as a NIC queue that should improve overall bandwidth for a large > > number of our users. The API there is definitely an ioctl() and the hard part is > > doing the tying together. To do this we need to also work out our low level story. > > But it would be a lot nicer if this could be done automatically. Which > I believe it can - see the RFS and XPS features in Linux. rwatson@ has been working on "connection groups" (not sure what he calls his project) with a goal to improve the placement of work in the FreeBSD network stack. Some of the code is in the kernel but the parts that require closer cooperation with a NIC are not. Regards, Navdeep
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