On Wed, Feb 20, 2013 at 11:59 AM, Lawrence Stewart <lstew...@freebsd.org> wrote: > Hi Sephe, > > On 02/20/13 13:37, Sepherosa Ziehau wrote: >> On Wed, Feb 20, 2013 at 9:46 AM, Lawrence Stewart <lstew...@room52.net> >> wrote: >>> *crickets chirping* >>> >>> Time to move this discussion forward... >>> >>> >>> If any robust counter-arguments exist, now is the time for us to hear >>> them. I haven't read anything thus far which convinces me that we should >>> not provide knobs to tune our stack's dynamics. >>> >>> In the absence of any compelling counter-arguments, I would like to >>> propose the following: >>> >>> - We rename the net.inet.tcp.experimental sysctl node introduced in >>> r242266 for IW10 support to net.inet.tcp.nonstandard, and re-parent the >>> initcwnd10 sysctl under this node. > > I should also add that I think initcwnd10 should be changed to initcwnd > and take the number of segments as a value.
Yeah, I would suggest the same. > >>> - We introduce a new net.inet.tcp.nonstandard.allowed sysctl variable >>> and default it to 0. Only when it is changed to 1 will we allow starkly >>> non standards compliant behaviour to be enabled in the stack. As a more >>> complex but expressive alternative, we can make the sysctl take a bit >>> mask or CSV string which specifies which non-standard options the sys >>> admin permits (I'd prefer this as we can easily test non-standard >>> options like IW10 in head without blanket enabling all non standard >>> behaviour). > > To be clear, my proposal is that specifying an allowed option in > net.inet.tcp.nonstandard.allowed would not enable it as the default on > all connections, but would allow the per-application mechanism we define > to set the option. Setting net.inet.tcp.nonstandard.option_x to 1 would > enable the option as default for all connections. > >>> - We introduce a new net.inet.tcp.nonstandard.noidlereset sysctl >>> variable, and use it to enable/disable window-reset-after-idle behaviour >>> as proposed by John. >>> >>> - We don't introduce a TF_IGNOREIDLE sockopt, and instead introduce a >>> more generic sockopt and/or mechanism for per-application tuning of all >>> options which affect stack dynamics (both standard and non-standard >>> options). I'm open to suggestions on what this could/should look like. >> >> Lawrence, >> >> A route metric? BTW, as for IW10, it could also become a route metric >> (as proposed by the draft author's presentation >> http://www.ietf.org/proceedings/79/slides/tcpm-0.pdf) > > Are you suggesting having the ability to set knobs as route metrics in > addition to sysctl and a per-app mechanism? If so then I am very much in > favour of this. Assuming an option has been allowed in > net.inet.tcp.nonstandard.allowed, it should be able to be set by an > application or on a route, perhaps with a precedence hierarchy of app > request trumps route metric trumps system default setting? I suggest using route metrics in addition to the global sysctls; route metrics take precedence over global sysctls. I don't object the per-socket settings though. However, IMHO, these options (IW10 and ignoring idle restart, and probably others) are administrative, so applications probably should not mess with them. Best Regards, sephe -- Tomorrow Will Never Die _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
