Hi > -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Newman Poborsky > Sent: Thursday, December 18, 2014 1:26 PM > To: dev at dpdk.org > Subject: [dpdk-dev] rte_mempool_create fails with ENOMEM > > 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.
Yes,rte_mempool_create uses rte_memzone_reserve() to allocate single physically continuous chunk of memory. If no such chunk exist, then it would fail. Why physically continuous? Main reason - to make things easier for us, as in that case we don't have to worry about situation when mbuf crosses page boundary. So you can overcome that problem like that: Allocate max amount of memory you would need to hold all mbufs in worst case (all pages physically disjoint) using rte_malloc(). Figure out it's physical mappings. Call rte_mempool_xmem_create(). You can look at: app/test-pmd/mempool_anon.c as a reference. It uses same approach to create mempool over 4K pages. We probably add similar function into mempool API (create_scatter_mempool or something) or just add a new flag (USE_SCATTER_MEM) into rte_mempool_create(). Though right now it is not there. Another quick alternative - use 1G pages. Konstantin > > 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.