surprise surprise (VM related) [luigi at FreeBSD.org: svn commit: r250911 - head/sys/kern]

[Ryan Stone]

On Wed, May 22, 2013 at 12:42 PM, Luigi Rizzo <rizzo at iet.unipi.it> wrote:

> all that work on paravirtualization (as presented at bsdcan)
>
> http://info.iet.unipi.it/~luigi/netmap/talk-bsdcan-2013.html
>
> just to discover that simply enabling DEVICE_POLLING (10-years old
> technology) gives the same performance gains plus livelock-avoidance.
>
> And no, linux's NAPI is nowhere near us.
>
>         cheers
>         luigi
>

A couple of years ago I started working on upstreaming some DEVICE_POLLING
improvements from $WORK that incorporated feedback from polled interfaces
to drive rescheduling of a polling iteration (rather than waiting for the
next hardclock() to reschedule polling) but I never finished it.  It works
fine, but I didn't get a chance to test performance.  It's available here:

https://gitorious.org/~rysto/freebsd/rystos-freebsd-head/commit/e27db681b96cced7d3128ad3268f2cbf7474925a


In the same repository I also have a branch that extends DEVICE_POLLING to
work with multiple netisr threads.