2025-02-19 15:22 (UTC+0100), Lucas: > I am creating an application where I want to cache packets in a ring for a > certain duration. To do so at high speed (100 Gb/s) for tens of seconds, I > would like to create a mempool with a size bigger than 500 GiB. > I know that in rte_config.h, we have this excerpt: > ``` > #define RTE_MAX_MEMSEG_LISTS 128 > ... > #define RTE_MAX_MEM_MB_PER_LIST 32768 > ``` > 4'194'304 MiB of addressable memory, which is more than enough. However, > there is a virtual memory limit on DPDK processes on x86_64, which appears > to be 512 GiB. > at https://doc.dpdk.org/guides/prog_guide/env_abstraction_layer.html it is > listed that RTE_MAX_MEM_MB controls that. > In the meson.build file in the config directory, we have: > ``` > if dpdk_conf.get('RTE_ARCH_64') > dpdk_conf.set('RTE_MAX_MEM_MB', 524288) > else # for 32-bit we need smaller reserved memory areas > dpdk_conf.set('RTE_MAX_MEM_MB', 2048) > endif > ``` > Changing this value does not seem to change the amount of virtual memory > that DPDK allocates. It appears that no headers or C-files actually > reference this value.
https://elixir.bootlin.com/dpdk/v24.11.1/source/lib/eal/common/eal_common_dynmem.c#L113 > What would I need to change to allow more virtual memory than 512 GiB and > be able to allocate a mempool with a size bigger than that? Increase RTE_MAX_MEM_MB_PER_LIST and RTE_MAX_MEM_MB_PER_TYPE to 512 GB. See the big comment in the linked function code. Note that RTE_MAX_MEM_MB must accommodate for all memory types, e.g. for a 2-processor x86_64 system with 2M and 1G hugepages supported it must be 2 NUMA nodes x 2 huggepage sizes x 512 GB = 2048 GB.
