On 07/24/2018 01:03 PM, Thomas Monjalon wrote: > 24/07/2018 13:04, Burakov, Anatoly: >> On 24-Jul-18 11:23 AM, Thomas Monjalon wrote: >>> 24/07/2018 12:03, Anatoly Burakov: >>>> It has been reported that current memory limitations do not work >>>> well on an 8-socket machines in default configuration when big >>>> page sizes are used [1]. >>>> >>>> Fix it by reducing memory amount reserved by DPDK by default to >>>> 32G per page size per NUMA node. This translates to allowing us >>>> to reserve 32G per page size per NUMA node on 8 nodes with 2 >>>> page sizes. >>>> >>>> [1] https://mails.dpdk.org/archives/dev/2018-July/108071.html >>>> >>>> Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com> >>>> --- >>>> >>>> Notes: >>>> We could have increased CONFIG_RTE_MAX_MEM_MB but this would've >>>> brought other potential problems due to increased memory >>>> preallocation, and secondary process initialization is flaky >>>> enough as it is. I am willing to bet that 32G per page size is >>>> more than enough for the majority of use cases, and any >>>> application with bigger requirements could adjust config options >>>> itself. >>> [...] >>>> -CONFIG_RTE_MAX_MEMSEG_PER_TYPE=32768 >>>> -CONFIG_RTE_MAX_MEM_MB_PER_TYPE=131072 >>>> +CONFIG_RTE_MAX_MEMSEG_PER_TYPE=16384 >>>> +CONFIG_RTE_MAX_MEM_MB_PER_TYPE=32768 >>> >>> Ideally, it should be a run-time option. >>> >> >> It can be, yes, and this can be worked on for next release. However, we >> also need to have good default values that work across all supported >> platforms. > > Yes sure, we can wait the next release for a run-time option. > > How can we be sure these default values are good enough?
Why add a new limitation? Why not take the other approach that was suggested of increasing the max possible memory? If there is new limitations or backwards compatibility issues with default settings compared with before the large memory management rework, then it would be good to have that clear in the docs at a high level for the users who want to update. It would also help a lot to add what the implications and limits for changing the most important defines are - will it be slower? will it not work above X? etc. > It would be good to have several acks from various projects or companies. > >
