Am Fri, 15 May 2020 18:29:44 -0700 schrieb Vinicius Costa Gomes <vinicius.go...@intel.com>:
> Hi, > > This series adds support for configuring frame preemption, as defined > by IEEE 802.1Q-2018 (previously IEEE 802.1Qbu) and IEEE 802.3br. > > Frame preemption allows a packet from a higher priority queue marked > as "express" to preempt a packet from lower priority queue marked as > "preemptible". The idea is that this can help reduce the latency for > higher priority traffic. > > Previously, the proposed interface for configuring these features was > using the qdisc layer. But as this is very hardware dependent and all > that qdisc did was pass the information to the driver, it makes sense > to have this in ethtool. > > One example, for retrieving and setting the configuration: > > $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 > Frame preemption settings for enp3s0: > support: supported > active: active > supported queues: 0xf > supported queues: 0xe > minimum fragment size: 68 > > > $ ethtool --set-frame-preemption enp3s0 fp on min-frag-size 68 > preemptible-queues-mask 0xe > > This is a RFC because I wanted to have feedback on some points: > > - The parameters added are enough for the hardware I have, is it > enough in general? What about the Qbu handshake state? And some NICs support overriding this. I.e. enable frame preemption even if the handshake wasn't successful. -michael > > - even with the ethtool via netlink effort, I chose to keep the > ioctl() way, in case someone wants to backport this to an older > kernel, is there a problem with this? > > - Some space for bikeshedding the names and location (for example, > does it make sense for these settings to be per-queue?), as I am > not quite happy with them, one example, is the use of preemptible > vs. preemptable; > > > About the patches, should be quite straightforward: > > Patch 1, adds the ETHTOOL_GFP and ETHOOL_SFP commands and the > associated data structures; > > Patch 2, adds the ETHTOOL_MSG_PREEMPT_GET and ETHTOOL_MSG_PREEMPT_SET > netlink messages and the associated attributes; > > Patch 3, is the example implementation for the igc driver, the catch > here is that frame preemption in igc is dependent on the TSN "mode" > being enabled; > > Patch 4, adds some registers that helped during implementation. > > Another thing is that because igc is still under development, to avoid > conflicts, I think it might be easier for the PATCH version of this > series to go through Jeff Kirsher's tree. > > Vinicius Costa Gomes (4): > ethtool: Add support for configuring frame preemption > ethtool: Add support for configuring frame preemption via netlink > igc: Add support for configuring frame preemption > igc: Add support for exposing frame preemption stats registers > > drivers/net/ethernet/intel/igc/igc.h | 3 + > drivers/net/ethernet/intel/igc/igc_defines.h | 6 + > drivers/net/ethernet/intel/igc/igc_ethtool.c | 77 ++++++++ > drivers/net/ethernet/intel/igc/igc_regs.h | 10 + > drivers/net/ethernet/intel/igc/igc_tsn.c | 46 ++++- > include/linux/ethtool.h | 6 + > include/uapi/linux/ethtool.h | 25 +++ > include/uapi/linux/ethtool_netlink.h | 19 ++ > net/ethtool/Makefile | 3 +- > net/ethtool/ioctl.c | 36 ++++ > net/ethtool/netlink.c | 15 ++ > net/ethtool/netlink.h | 2 + > net/ethtool/preempt.c | 181 > +++++++++++++++++++ 13 files changed, 423 insertions(+), 6 > deletions(-) create mode 100644 net/ethtool/preempt.c >
