> On Dec 1, 2014, at 7:49 AM, John Baldwin <j...@freebsd.org> wrote: > >> On Monday, December 01, 2014 07:19:13 AM Alfred Perlstein wrote: >> John, >> >> Will work on a new revision based on feedback. >> >> Two things to note however: >> >> Already explored the idea of using kernel_sysctlbyname but rejected due to >> following: >> >> It makes little sense to have a rw sysctl that only takes effect "some >> times". This violates POLA at the expense of making code appear cleaner. >> Expectation is that writable sysctls take effect or are read only. They are >> not to be "write sometimes" unless we are to introduce a new flag. Instead >> of going to a confusing model we consider some form of rw sysctl that can >> set itself ro somehow. Otherwise people will be confused as to why nic >> queues says N while actually M. What the rw->ro api would look like I have >> no idea. Suggestions? > > This is only somewhat true. In the near distant future we will have a devctl > tool which would let you do 'devctl detach igb0 && devctl attach igb0' which > would honor your post-boot setting of hw.igb.num_queues. Instead what is > important to understand about this particular sysctl node is that it only > takes affect when a device is attached. However, there are other control > knobs that also only affect future operations and not existing instances of > objects, so I don't think this is that big of a leap. >
Strongly disagree here. If I were not able to grok the c code I would be very confused by such a thing. In fact even with the fact that I do grok c code I would be very discouraged to find such behavior and strongly object to writable sysctls that do nothing. The ux is that the user has a bunch of dials on their dashboard that function as a busybox as opposed to doing what they are advertised to do. Sort of like those crossing light buttons in New York City that aren't actually hooked to anything. So: No. Frankly would rather back out the change entirely and keep this change local to us than expose users to such a UX. I will however like to discuss the possibility of a tunable/sysctl system that makes sense. -Alfred. > -- > John Baldwin > _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
