On 14-Jul-18 10:44 AM, Kumar, Ravi1 wrote:
Memory setup with 2M pages works with the default configuration. With
the default configuration and 2M hugepages
1. Total amount of memory for each NUMA zone does not exceed
128G (CONFIG_RTE_MAX_MEM_MB_PER_TYPE).
2. Total number of segment lists per NUMA is limited to 32768
(CONFIG_RTE_MAX_MEMSEG_PER_TYPE). This constraint is met for each numa
zone. This is the limiting factor for memory per numa with 2M hugepages
and the default configuration.
3. The data structures are capable of supporting 64G of
memory for each numa zone (32768 segments * 2M hugepagesize).
4. 8 NUMA zones * 64G = 512G. Therefore the total for all
numa zones does not exceed 512G (CONFIG_RTE_MAX_MEM_MB).
5. Resources are capable of allocating up to 64G per NUMA
zone. Things will work as long as there are enough 2M hugepages to
cover the memory needs of the DPDK applications AND no memory zone
needs more than 64G.
With the default configuration and 1G hugepages
1. Total amount of memory for each NUMA zone is limited to
128G (CONFIG_RTE_MAX_MEM_MB_PER_TYPE). This constraint is hit for each
numa zone. This is the limiting factor for memory per numa.
2. Total number of segment lists (128) does not exceed 32768
(CONFIG_RTE_MAX_MEMSEG_PER_TYPE). There are 128 segments per NUMA.
3. The data structures are capable of supporting 128G of
memory for each numa zone (128 segments * 1G hugepagesize). However,
only the first four NUMA zones get initialized before we hit
CONFIG_RTE_MAX_MEM_MB (512G).
4. The total for all numa zones is limited to 512G
(CONFIG_RTE_MAX_MEM_MB). This limit is hit after configuring the
first four NUMA zones (4 x 128G = 512G). The rest of the NUMA zones
cannot allocate memory.
Apparently, it is intended to support max 8 NUMAs by default
(CONFIG_RTE_MAX_NUMA_NODES=8), but when 1G hugepages are use, it can
only support up to 4 NUMAs.
Possible workarounds when using 1G hugepages:
1. Decrease CONFIG_RTE_MAX_MEM_MB_PER_TYPE to 65536 (limit of
64G per NUMA zone). This is probably the best option unless you need a
lot of memory in any given NUMA.
2. Or, increase CONFIG_RTE_MAX_MEM_MB to 1048576.
Hi Ravi,
OK this makes it much clearer, thanks!
I think the first one should be done. I think 64G per NUMA node is still
a reasonable amount of memory and it makes the default work (i think we
can go as far as reducing this limit to 32G per type!), and whoever has
issues with it can change CONFIG_RTE_MAX_MEM_MB_PER_TYPE or
CONFIG_RTE_MAX_MEM_MB for their use case. That's what these options are
there for :)
--
Thanks,
Anatoly
