A RSS value of anything other than 1 results in 100% packet drops for ixgbe driver

[jnicholls]

For some reason, if I either omit the RSS value, or set it to anything other than 1, PF_RING will drop all packets. Is this to be expected? What would cause that behavior? It seems counter-intuitive that a single RX queue would perform better than multiple RX queues. It's as if the PF_RING library has internally deadlocked in its worker thread.

Does one have to do anything differently in userland to properly use multiple RX queues? What's the benefit/cost tradeoffs to having a single vs. multiple RX queues?

Thanks!

[cardigliano]

If you are using ZC, you are probably capturing from the first queue only (ethX == ethX@0),
you should explicitly capture from all the queues when multiqueue is enabled. You have benefits
using multithreaded/multiprocess applications, otherwise better to use 1 queue.

Alfredo

On 17 Aug 2015, at 12:37, Jarred Nicholls notifications@github.com wrote:

For some reason, if I either omit the RSS value, or set it to anything other than 1, PF_RING will drop all packets. Is this to be expected? What would cause that behavior? It seems counter-intuitive that a single RX queue would perform better than multiple RX queues. It's as if the PF_RING library has internally deadlocked in its worker thread.

Does one have to do anything differently in userland to properly use multiple RX queues? What's the benefit/cost tradeoffs to having a single vs. multiple RX queues?

Thanks!

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Reply to this email directly or view it on GitHub #35.

[jnicholls]

Thanks Alfreda. How are the packets distributed amongst the queues? Is there any control over this? Thanks.

[cardigliano]

RSS hash is based on src/dst ip and port (bidirectional thanks to the ZC library reprogramming the hw hashing function),
thus traffic gets load-balanced across queues based on sessions (flows).

Alfredo

On 31 Aug 2015, at 20:27, Jarred Nicholls notifications@github.com wrote:

Thanks Alfreda. How are the packets distributed amongst the queues? Is there any control over this? Thanks.

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Reply to this email directly or view it on GitHub #35 (comment).