I've Also seen a similar issue when trying to run a dpdk app which allocates huge pools(~0.5GB) after a memory heavy operation on the machine.
I've come to the same conclusion as you did, that internal fragmentation is causing pool creation failures. It seems that the rte_mempool_xmem_create/rte_memzone_reserve_aligned are attempting to create physicaly contiguous pools. Which may offer a slight performance gain(?) but may cause unpredictable allocation issues which is a big risk for DC deployments where hundreds or even thousands of machines may be deployed with a dpdk app and fail inexplicably. I didn't really get the chance to digg into the memory managment internals of DPDK, so feel free to correct me where I'm off. Thanks. On Thu, Dec 18, 2014 at 3:25 PM, Newman Poborsky <newman555p at gmail.com> wrote: > > Hi, > > could someone please provide any explanation why sometimes mempool creation > fails with ENOMEM? > > I run my test app several times without any problems and then I start > getting ENOMEM error when creating mempool that are used for packets. I try > to delete everything from /mnt/huge, I increase the number of huge pages, > remount /mnt/huge but nothing helps. > > There is more than enough memory on server. I tried to debug > rte_mempool_create() call and it seems that after server is restarted free > mem segments are bigger than 2MB, but after running test app for several > times, it seems that all free mem segments have a size of 2MB, and since I > am requesting 8MB for my packet mempool, this fails. I'm not really sure > that this conclusion is correct. > > Does anybody have any idea what to check and how running my test app > several times affects hugepages? > > For me, this doesn't make any since because after test app exits, resources > should be freed, right? > > This has been driving me crazy for days now. I tried reading a bit more > theory about hugepages, but didn't find out anything that could help me. > Maybe it's something else and completely trivial, but I can't figure it > out, so any help is appreciated. > > Thank you! > > BR, > Newman P. >
