This is very useful. Thank you very much Siobhan. Thanks M Jay
-----Original Message----- From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Siobhan Butler Sent: Sunday, March 22, 2015 6:25 AM To: dev at dpdk.org Subject: [dpdk-dev] [PATCH] doc: added to faq section of release notes Added some of the questions posted to the mailing list to the FAQ section of release notes. Signed-off-by: Siobhan Butler <siobhan.a.butler at intel.com> --- doc/guides/rel_notes/faq.rst | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/doc/guides/rel_notes/faq.rst b/doc/guides/rel_notes/faq.rst index 054db10..14b1167 100644 --- a/doc/guides/rel_notes/faq.rst +++ b/doc/guides/rel_notes/faq.rst @@ -191,3 +191,38 @@ In this case, this has to be done manually on the VM host, using the following c where <interface> being the interface providing the virtual functions for example, eth0, <VF function> being the virtual function number, for example 0, and <MAC address> being the desired MAC address. + +Is it safe to add an entry to the hash table while running? +------------------------------------------------------------ +Currently the table implementation is not a thread safe implementation and assumes that locking between threads and processes is handled by the user's application. +This is likely to be supported in future releases. + +What is the purpose of setting iommu=pt? +---------------------------------------- +DPDK uses a 1:1 mapping and does not support IOMMU. IOMMU allows for simpler VM physical address translation. +The second role of IOMMU is to allow protection from unwanted memory access by an unsafe device that has DMA privileges. +Unfortunately, the protection comes with an extremely high perfomance cost for high speed NICs. + +iommu=pt disables IOMMU support for the hypervisor. + +When trying to send packets from an application to itself, meaning smac==dmac, using Intel(R) 82599 VF packets are lost. +----------------------------------------------------------------------- +------------------------------------------------- +Check on register LLE(PFVMTXSSW[n]), which allows an individual pool to send traffic and have it looped back to itself. + +Can I split packet RX to use DPDK and have an application's higher order functions continue using Linux* pthread? +----------------------------------------------------------------------- +------------------------------------------ +The DPDK's lcore threads are Linux* pthreads bound onto specific cores. +Configure the DPDK to do work on the same cores and run the +application's other work on other cores using the DPDK's "coremask" setting to specify which cores it should launch itself on. + +Is it possible to exchange data between DPDK processes and regular userspace processes via some shared memory or IPC mechanism? +----------------------------------------------------------------------- +-------------------------------------------------------- +Yes - DPDK processes are regular Linux/BSD processes, and can use all OS provided IPC mechanisms. + +Can the multiple queues in Intel(R) I350 be used with DPDK? +----------------------------------------------------------- +I350 has RSS support and 8 queue pairs can be used in RSS mode. It should work with multi-queue DPDK applications using RSS. + +How can hugepage-backed memory be shared among multiple processes? +------------------------------------------------------------------ +See the Primary and Secondary examples in the multi-process sample application. -- 1.8.3.1
