Re: [SPDK] No free hugepages reported in hugepages

Re: [SPDK] No free hugepages reported in hugepages

[Walker, Benjamin]

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On Wed, 2017-07-19 at 14:02 +0530, Oza Oza wrote:
> Hi All,
>  
> 1)      DPDK fails if huge-pages are not reserved. But should not it fall back
> to regular 4k pages ?

Hugepages are not just used for efficiency reasons - they're used as a way to
get DMA safe memory in user space. I wrote an extensive overview of the
challenges in this area here:

http://www.spdk.io/doc/memory.html


> 2)      And how user space should know the requirement of number of hug pages
> before-hand ?
> a.      Rather should it always be reserved before-hand in the system?, with
> that we might waste some.

I agree that this is a real usability challenge and a more dynamic memory
allocator for hugepages would be a great leap forward for both DPDK and SPDK.
Until we get to that point, you have to pre-reserve pages and you'll probably
waste some amount of memory.

>  
>  
>  
> Regards,
> Oza.
> _______________________________________________
> SPDK mailing list
> SPDK(a)lists.01.org
> https://lists.01.org/mailman/listinfo/spdk

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[SPDK] No free hugepages reported in hugepages

[Oza Oza]

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Hi All,



1)      DPDK fails if huge-pages are not reserved. But should not it fall
back to regular 4k pages ?

2)      And how user space should know the requirement of number of hug
pages before-hand ?

a.      Rather should it always be reserved before-hand in the system?,
with that we might waste some.



root(a)bcm958742t:~# /usr/share/spdk/examples/nvme/perf -r 'trtype:PCIe
traddr:0000:01:00.0' -q 128 -s 4096 -w write -d 2048 -t 30 -c 0x1

Starting DPDK 16.11.1 initialization...

[ DPDK EAL parameters: perf -c 1 -m 2048 --file-prefix=spdk_pid3[
187.734815] audit: type=1701 audit(1500448013.777:3): auid=4294967295 uid=0
gid=0 ses=4294967295 pid=3465 comm="perf"
exe="/usr/share/spdk/examples/nvme/perf" sig=6 res=1

465 ]

EAL: Detected 8 lcore(s)

EAL: No free hugepages reported in hugepages-2048kB

PANIC in rte_eal_init():

Cannot get hugepage information

1: [/usr/share/spdk/examples/nvme/perf() [0x4197d4]]

Aborted (core dumped)





Regards,

Oza.

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