From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinicius Costa Gomes Date: Mon, 11 Apr 2022 16:36:42 -0700 Subject: [Intel-wired-lan] [PATCH net-next v4 11/12] igc: Check incompatible configs for Frame Preemption In-Reply-To: <20210628092003.bribdjfaxwnpdt5f@skbuf> References: <20210626003314.3159402-1-vinicius.gomes@intel.com> <20210626003314.3159402-12-vinicius.gomes@intel.com> <20210628092003.bribdjfaxwnpdt5f@skbuf> Message-ID: <87wnfvchv9.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: Vladimir Oltean writes: > On Fri, Jun 25, 2021 at 05:33:13PM -0700, Vinicius Costa Gomes wrote: >> Frame Preemption and LaunchTime cannot be enabled on the same queue. >> If that situation happens, emit an error to the user, and log the >> error. >> >> Signed-off-by: Vinicius Costa Gomes >> --- > > This is a very interesting limitation, considering the fact that much of > the frame preemption validation that I did was in conjunction with > tc-etf and SO_TXTIME (send packets on 2 queues, one preemptible and one > express, and compare the TX timestamps of the express packets with their > scheduled TX times). The base-time offset between the ET and the PT > packets is varied in small increments in the order of 20 ns or so. > If this is not possible with hardware driven by igc, how do you know it > works properly? :) Good question. My tests were much less accurate than what you were doing, I was basically flooding the link with preemptable packets, and sending some number of express packets, and counting them using some debug counters on the receiving side. Cheers, -- Vinicius