> -----Original Message----- > From: Van Haaren, Harry > Sent: Thursday, July 14, 2022 5:54 PM > To: Pavan Nikhilesh Bhagavatula <[email protected]>; mattias.ronnblom > <[email protected]>; Thomas Monjalon <[email protected]> > Cc: Jerin Jacob Kollanukkaran <[email protected]>; Ray Kinsella > <[email protected]>; > [email protected]; McDaniel, Timothy <[email protected]>; Hemant > Agrawal <[email protected]>; [email protected]; > [email protected]; Mccarthy, Peter <[email protected]>; Carrillo, > Erik > G <[email protected]>; Gujjar, Abhinandan S > <[email protected]>; Jayatheerthan, Jay > <[email protected]>; > Burakov, Anatoly <[email protected]> > Subject: RE: [EXT] Re: [PATCH 1/2] doc: add enqueue depth for new event type > > > -----Original Message----- > > From: Pavan Nikhilesh Bhagavatula <[email protected]> > > Sent: Thursday, July 14, 2022 5:42 PM > > To: mattias.ronnblom <[email protected]>; Thomas Monjalon > > <[email protected]> > > Cc: Jerin Jacob Kollanukkaran <[email protected]>; Ray Kinsella > <[email protected]>; > > [email protected]; McDaniel, Timothy <[email protected]>; Hemant > > Agrawal <[email protected]>; [email protected]; > > [email protected]; Mccarthy, Peter <[email protected]>; Van > Haaren, > > Harry <[email protected]>; Carrillo, Erik G > > <[email protected]>; > > Gujjar, Abhinandan S <[email protected]>; Jayatheerthan, Jay > > <[email protected]>; Burakov, Anatoly <[email protected]> > > Subject: RE: [EXT] Re: [PATCH 1/2] doc: add enqueue depth for new event type > > <snip old conversation> > > > > >> If the underlying hardware has some limitations, > > > >> why not let the driver loop until back pressure occurs? Then you can > > > > > > You didn't answer this question. Why not let the driver loop, until you > > > for some reason or the other can't accept more events? > > > > CNXK event driver cannot accept forwarding(enq) more than one event that has > > been dequeued. Enqueueing more than one event for forwarding/releasing > > is a violation from HW perspective, this is currently announced by BURST > capability. > > But It can enqueue a burst if new events. > > Can't the driver just backpressure NEW events? that's what the event/sw driver > does in order to limit "new" inflight events. App attempts to enq FWD/REL, no > problem. App enqueues burst of NEW (and there's only N spaces) then the > first N events pass, and the rest are returned to the application. > > > If you see the current example implementation we pick the worker based on > > BURST capability for optimizing the enqueue/dequeue by providing a hint > > to the driver layer. > > Please provide a link to the code? Others are not familiar with the CNXK > driver, > or the sample code you're referring to... > > > > Although, we could live with aggregating the events at driver layer based on > > queue. We would still require announce burst capability for new events i.e. > > changes to the info structure. > > As per above, I still don't see a reason why this HW optimization/limitation > needs to be pushed to the application layer. Why can the driver not handle > things by allowing/backpressure to the events it can/can't handle? > > > In this email thread[1] you've suggested reworking the rx_burst API with a > flag to indicate "same destination". This still pushes the problem to the > application, > and exposes more HW/PMD specific options. This impl is *slightly* better > because it > wont' require new APIs for each mode, but also *breaks all existing apps*!? > > I'm just not understanding why the application needs to change, and why it > cannot be optimized/handled in the driver layer. > > [1] http://mails.dpdk.org/archives/dev/2022-July/246717.html > > <snip old conversation>
Let me be very clear, but also try to help here; I'm not in favour of the changes as proposed here, and feel that pushing the problem to Application API is NOT the right solution. But *just in case* there is a *genuine* reason that we need an API/ABI change, and that can be justified clearly in the upcoming weeks, then I'd prefer not have problems with the deprecation notice not being included. This Ack is *only* to allow possible API/ABI changes in 22.11, and not for the proposal above. Acked-by: Harry van Haaren <[email protected]>
