+TO: Qiming Yang, author of the patch. +CC: stable > From: Edwin Brossette [mailto:[email protected]] > Sent: Thursday, 30 November 2023 12.25 > > Hello, > > We recently started to observe concerning behaviour on our continuous > integration platform following this commit, which set the maximum amount of > tx/rx queues at 2 for the e1000 pmd: > > net/e1000: fix queue number initialization > https://git.dpdk.org/dpdk/commit/?id=c1a42d646472fd3477429bf016f682e0865b77f0 > > Reverting this change locally on our side was enough to fix our test issues. > > There is a considerately long explanation in a comment just above the change > explaining why the number of rx/tx queues is limited at 1, yet it was changed > at 2 anyway.
For reference, here is the explanation in the source code: <quote> Starting with 631xESB hw supports 2 TX/RX queues per port. Unfortunatelly, all these nics have just one TX context. So we have few choises for TX: - Use just one TX queue. - Allow cksum offload only for one TX queue. - Don't allow TX cksum offload at all. For now, option #1 was chosen. To use second RX queue we have to use extended RX descriptor (Multiple Receive Queues are mutually exclusive with UDP fragmentation and are not supported when a legacy receive descriptor format is used). Which means separate RX routinies - as legacy nics (82540, 82545) don't support extended RXD. To avoid it we support just one RX queue for now (no RSS). </quote> > > Since I couldn't see any mention in logs about theses restrictions being > removed, I wished to inquire whether this change was truly intended and if > there was any problem which motivated it. Qiming, what is the explanation, please? > Maybe the max number of rx/tx queues should reverted back to 1? Or maybe the > comment should be updated if limitations are no longer true? Your CI platform flagging problems is a strong indicator of something being wrong. So I would guess the limitations are still true, and the max number of rx/tx queues should be reverted back to 1. If someone really needs 2 queues, perhaps it could be a build time option to enable 2 queues without offloads. Qiming, what do you think? > > Regards, > Edwin Brossette.
