Hi David, We have certain use cases where certain threads can sleep and help us with power saving And there are certain scenarios in which the pmd threads handle heartbeats and are sensitive to latency. so, either these threads wake up on an rx-interrupt so effectively(UMWAIT) that no significant latency is observed Or maybe having an option with which we can decide which PMD threads sleep and which PMD thread continues to Poll. so that the user can use rxq_affinity to pick the right PMD based on the traffic profile that is received on that interface.
Thanks Thilak Raj S -----Original Message----- From: David Marchand <[email protected]> Sent: 01 December 2022 00:47 To: Thilak Raj Surendra Babu <[email protected]> Cc: [email protected]; Karthik Chandrashekar <[email protected]>; Kevin Traynor <[email protected]>; Christophe Fontaine <[email protected]> Subject: Re: [ovs-dev] [RFC PATCH v2] dpif-netdev: Put idle PMD threads to sleep. On Wed, Nov 30, 2022 at 9:20 PM Thilak Raj Surendra Babu <[email protected]> wrote: > > For my understanding, is part being woken up by a RX interrupt not desirable? Latency is one thing that could be enhanced with Rx interrupt. Maybe you have another usecase that would make Rx interrupts a better fit than simply sleeping. If so, please share details. On our side, we are focusing on power savings atm as big deployments put a high priority on this topic. So Kevin approach seems more interesting, at least as a first step, because we get some power saving even at low rates. > I am under the assumption that all NICs do support rx-interrupts through the > fd. In theory, I would assume too that we can have rx interrupts for hw drivers (unless we use some old hw, or because of some hw bug...). If hw is accessed through vfio, we get eventfds mapped to MSIX. Drivers like mlx (implemented on top of rdma api) provide some fd too. Even so, you'll see that a fair number of DPDK drivers do not have support. As for the reason, it may be by lack of interest so far. > Will take a look at Kevin's patch and try it out as well. Thanks. -- David Marchand _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
