Re: [dpdk-users] qos_sched in DPDK 17.11.0 fails to initialize mbuf pool

["Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>]

> -----Original Message-----
> From: Ian Trick [mailto:ian.trick@multapplied.net]
> Sent: Friday, November 17, 2017 5:50 PM
> To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>; users@dpdk.org
> Subject: Re: qos_sched in DPDK 17.11.0 fails to initialize mbuf pool
> 
> On 2017-11-17 04:19 AM, Dumitrescu, Cristian wrote:
> >
> >
> >> -----Original Message-----
> >> From: Ian Trick [mailto:ian.trick@multapplied.net]
> >> Sent: Friday, November 17, 2017 1:24 AM
> >> To: users@dpdk.org
> >> Cc: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> >> Subject: qos_sched in DPDK 17.11.0 fails to initialize mbuf pool
> >>
> >> Hi. I'm having an issue starting the qos_sched example program.
> >>
> >> # ./examples/qos_sched/build/qos_sched --no-huge -l 1,2,3 --vdev
> >> net_af_packet0,iface=eth1 -- --pfc "0,0,2,3" --cfg
> >> examples/qos_sched/profile_ov.cfg
> >>
> >> EAL: Detected 16 lcore(s)
> >> EAL: Probing VFIO support...
> >> EAL: Started without hugepages support, physical addresses not available
> >> EAL: PCI device 0000:08:00.0 on NUMA socket -1
> >> EAL:   Invalid NUMA socket, default to 0
> >> EAL:   probe driver: 8086:10d3 net_e1000_em
> >> PMD: Initializing pmd_af_packet for net_af_packet0
> >> PMD: net_af_packet0: AF_PACKET MMAP parameters:
> >> PMD: net_af_packet0:    block size 4096
> >> PMD: net_af_packet0:    block count 256
> >> PMD: net_af_packet0:    frame size 2048
> >> PMD: net_af_packet0:    frame count 512
> >> PMD: net_af_packet0: creating AF_PACKET-backed ethdev on numa
> socket 0
> >> EAL: Error - exiting with code: 1
> >>   Cause: Cannot init mbuf pool for socket 0
> >>
> >
> > Personally I never used this application with --no-huge or with AF_PACKET,
> so I suggest you start from the configuration known to work (as detailed in
> the Sample App Guide) and then change/add one variable at a time to see
> which change triggers the mempool issue.
> >
> > This app needs large amounts of memory for the mempool, as traffic
> management is buffering lots of packets in lots of queues. Out typical tests
> are done with 4K pipes/output port (64K queues/output port) so we
> provision mempool to have 2M buffers for each output port. The size of the
> mempool is hardcoded in the application.
> 
> Can I configure this to run with fewer queues or something so that it
> requires less memory. I thought running with profile_ov.cfg might have
> lower memory requirements since it includes:
> > number of pipes per subport = 32
> compared to 4096 in the other configuration file. So I figured there
> would be fewer queues and buffers? But I only have 4GB available on the
> device I have if I want to test something that isn't AF_PACKET.
> 

Digging in the source code, I found that you can tweak the mempool size through this macro:
//file "main.h"
#define NB_MBUF   (2*1024*1024)

> >
> >>
> >> This is version 17.11.0 from the repo. My RTE_TARGET is
> >> x86_64-native-linuxapp-clang. eth1 is a veth. I've tried running with
> >> `-m` and using a low value but the issue still happens.
> >>
> >> From what I can tell, rte_pktmbuf_pool_create() is failing and rte_errno
> >> is set to EINVAL.
> >>
> >> In librte_mempool/rte_mempool.c, the function
> >> rte_mempool_populate_virt() is succeeding this test and returning -
> EINVAL:
> >>
> >> 	if (RTE_ALIGN_CEIL(len, pg_sz) != len)
> >> 		return -EINVAL;
> >>
> >> In that context, len is mz->len, the length of a memzone passed by the
> >> caller, rte_mempool_populate_default(). Which got it here:
> >>
> >> 	mz = rte_memzone_reserve_aligned(mz_name, size,
> >> 		mp->socket_id, mz_flags, align);
> >> 	/* not enough memory, retry with the biggest zone we have */
> >> 	if (mz == NULL)
> >> 		mz = rte_memzone_reserve_aligned(mz_name, 0,
> >> 			mp->socket_id, mz_flags, align);
> >>
> >> This fails the first call, and succeeds the second when it passes 0 as
> >> the size. memzone_reserve_aligned_thread_unsafe(), in
> >> librte_eal/common/eal_common_memzone.c, gets the length this way:
> >>
> >> 	requested_len = find_heap_max_free_elem(&socket_id, align);
> >>
> >> So the align value is 4096. But the value returned by
> >> find_heap_max_free_elem() isn't aligned to that -- I think? Since it
> >> fails the check later on.
> >>
> >> I'm not sure if this is a thing with my environment where I don't have
> >> enough memory? (Although I would have expected a different error for
> >> that.) Or I don't have the right program arguments? Or one of these
> >> functions isn't doing what it's supposed to?