> -----Original Message----- > From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Elo, Matias (Nokia - > FI/Espoo) > Sent: Tuesday, May 7, 2019 5:33 PM > To: Mattias Rönnblom <hof...@lysator.liu.se> > Cc: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>; > dev@dpdk.org; nd <n...@arm.com> > Subject: Re: [dpdk-dev] eventdev: sw rx adapter enqueue caching > > > > On 7 May 2019, at 15:01, Mattias Rönnblom > <hof...@lysator.liu.se<mailto:hof...@lysator.liu.se>> wrote: > > > > On 2019-05-07 13:12, Honnappa Nagarahalli wrote: > > Hi, > > The SW eventdev rx adapter has an internal enqueue buffer 'rx_adapter- > event_enqueue_buffer', which stores packets received from the NIC until at > least BATCH_SIZE (=32) packets have been received before enqueueing them > to eventdev. For example in case of validation testing, where often a small > number of specific test packets is sent to the NIC, this causes a lot of > problems. One would always have to transmit at least BATCH_SIZE test > packets before anything can be received from eventdev. Additionally, if the > rx > packet rate is slow this also adds a considerable amount of additional delay. > > Looking at the rx adapter API and sw implementation code there doesn’t > seem to be a way to disable this internal caching. In my opinion this > “functionality" makes testing sw rx adapter so cumbersome that either the > implementation should be modified to enqueue the cached packets after a > while (some performance penalty) or there should be some method to > disable caching. Any opinions how this issue could be fixed? > At the minimum, I would think there should be a compile time option. > From a use case perspective, I think it falls under latency vs throughput > considerations. If there is a latency sensitive application, it might not want > to wait till 32 packets are received. > > From what I understood from Matias Elo and also after a quick glance in the > code, the unlucky packets will be buffered indefinitely, in case the system > goes idle. This is totally unacceptable (both in production and validation), > in > my opinion, and should be filed as a bug. > > > Indeed, this is what happens. I’ll create a bug report to track this issue. > I have posted a patch for this issue http://patchwork.dpdk.org/patch/53350/
Please let me know your comments. Thanks, Nikhil
