[dpdk-dev] [PATCH] mem: balanced allocation of hugepages

Ilya Maximets i.maximets at samsung.com
Mon Mar 27 16:43:15 CEST 2017


On 27.03.2017 16:01, Sergio Gonzalez Monroy wrote:
> On 09/03/2017 12:57, Ilya Maximets wrote:
>> On 08.03.2017 16:46, Sergio Gonzalez Monroy wrote:
>>> Hi Ilya,
>>>
>>> I have done similar tests and as you already pointed out, 'numactl --interleave' does not seem to work as expected.
>>> I have also checked that the issue can be reproduced with quota limit on hugetlbfs mount point.
>>>
>>> I would be inclined towards *adding libnuma as dependency* to DPDK to make memory allocation a bit more reliable.
>>>
>>> Currently at a high level regarding hugepages per numa node:
>>> 1) Try to map all free hugepages. The total number of mapped hugepages depends if there were any limits, such as cgroups or quota in mount point.
>>> 2) Find out numa node of each hugepage.
>>> 3) Check if we have enough hugepages for requested memory in each numa socket/node.
>>>
>>> Using libnuma we could try to allocate hugepages per numa:
>>> 1) Try to map as many hugepages from numa 0.
>>> 2) Check if we have enough hugepages for requested memory in numa 0.
>>> 3) Try to map as many hugepages from numa 1.
>>> 4) Check if we have enough hugepages for requested memory in numa 1.
>>>
>>> This approach would improve failing scenarios caused by limits but It would still not fix issues regarding non-contiguous hugepages (worst case each hugepage is a memseg).
>>> The non-contiguous hugepages issues are not as critical now that mempools can span over multiple memsegs/hugepages, but it is still a problem for any other library requiring big chunks of memory.
>>>
>>> Potentially if we were to add an option such as 'iommu-only' when all devices are bound to vfio-pci, we could have a reliable way to allocate hugepages by just requesting the number of pages from each numa.
>>>
>>> Thoughts?
>> Hi Sergio,
>>
>> Thanks for your attention to this.
>>
>> For now, as we have some issues with non-contiguous
>> hugepages, I'm thinking about following hybrid schema:
>> 1) Allocate essential hugepages:
>>     1.1) Allocate as many hugepages from numa N to
>>          only fit requested memory for this numa.
>>     1.2) repeat 1.1 for all numa nodes.
>> 2) Try to map all remaining free hugepages in a round-robin
>>     fashion like in this patch.
>> 3) Sort pages and choose the most suitable.
>>
>> This solution should decrease number of issues connected with
>> non-contiguous memory.
> 
> Sorry for late reply, I was hoping for more comments from the community.
> 
> IMHO this should be default behavior, which means no config option and libnuma as EAL dependency.
> I think your proposal is good, could you consider implementing such approach on next release?

Sure, I can implement this for 17.08 release.

>>
>>> On 06/03/2017 09:34, Ilya Maximets wrote:
>>>> Hi all.
>>>>
>>>> So, what about this change?
>>>>
>>>> Best regards, Ilya Maximets.
>>>>
>>>> On 16.02.2017 16:01, Ilya Maximets wrote:
>>>>> Currently EAL allocates hugepages one by one not paying
>>>>> attention from which NUMA node allocation was done.
>>>>>
>>>>> Such behaviour leads to allocation failure if number of
>>>>> available hugepages for application limited by cgroups
>>>>> or hugetlbfs and memory requested not only from the first
>>>>> socket.
>>>>>
>>>>> Example:
>>>>>      # 90 x 1GB hugepages availavle in a system
>>>>>
>>>>>      cgcreate -g hugetlb:/test
>>>>>      # Limit to 32GB of hugepages
>>>>>      cgset -r hugetlb.1GB.limit_in_bytes=34359738368 test
>>>>>      # Request 4GB from each of 2 sockets
>>>>>      cgexec -g hugetlb:test testpmd --socket-mem=4096,4096 ...
>>>>>
>>>>>      EAL: SIGBUS: Cannot mmap more hugepages of size 1024 MB
>>>>>      EAL: 32 not 90 hugepages of size 1024 MB allocated
>>>>>      EAL: Not enough memory available on socket 1!
>>>>>           Requested: 4096MB, available: 0MB
>>>>>      PANIC in rte_eal_init():
>>>>>      Cannot init memory
>>>>>
>>>>>      This happens beacause all allocated pages are
>>>>>      on socket 0.
>>>>>
>>>>> Fix this issue by setting mempolicy MPOL_PREFERRED for each
>>>>> hugepage to one of requested nodes in a round-robin fashion.
>>>>> In this case all allocated pages will be fairly distributed
>>>>> between all requested nodes.
>>>>>
>>>>> New config option RTE_LIBRTE_EAL_NUMA_AWARE_HUGEPAGES
>>>>> introduced and disabled by default because of external
>>>>> dependency from libnuma.
>>>>>
>>>>> Cc:<stable at dpdk.org>
>>>>> Fixes: 77988fc08dc5 ("mem: fix allocating all free hugepages")
>>>>>
>>>>> Signed-off-by: Ilya Maximets<i.maximets at samsung.com>
>>>>> ---
>>>>>    config/common_base                       |  1 +
>>>>>    lib/librte_eal/Makefile                  |  4 ++
>>>>>    lib/librte_eal/linuxapp/eal/eal_memory.c | 66 ++++++++++++++++++++++++++++++++
>>>>>    mk/rte.app.mk                            |  3 ++
>>>>>    4 files changed, 74 insertions(+)
> 
> Acked-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy at intel.com>

Thanks.

Best regards, Ilya Maximets.


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