On Wed, Sep 12, 2018 at 1:42 PM Florian Fainelli <f.faine...@gmail.com> wrote: > > > > On 9/9/2018 3:44 PM, Willem de Bruijn wrote: > > From: Willem de Bruijn <will...@google.com> > > > > Implement ethtool .set_coalesce (-C) and .get_coalesce (-c) handlers. > > Interrupt moderation is currently not supported, so these accept and > > display the default settings of 0 usec and 1 frame. > > > > Toggle tx napi through a bit in tx-frames. So as to not interfere > > with possible future interrupt moderation, use bit 10, well outside > > the reasonable range of real interrupt moderation values. > > > > Changes are not atomic. The tx IRQ, napi BH and transmit path must > > be quiesced when switching modes. Only allow changing this setting > > when the device is down. > > Humm, would not a private ethtool flag to switch TX NAPI on/off be more > appropriate rather than use the coalescing configuration API here?
What do you mean by private ethtool flag? A new field in ethtool --features (-k)? Configurable napi-tx is not a common feature across devices. We really want virtio-net to also just convert to napi-tx as default, but need a way to gradually convert with application opt-out if some workloads see regressions. There is prior art in interpreting coalesce values as more than a direct mapping to usec. The e1000 is one example.
