arm64: mremap size mismatch

[vielmetti]

"charm kv" is not working right on an arm64 system (Raspberry Pi, Debian Buster).

> charm kv list
foo     bar
~ ......................................................................................................................
> charm kv set foo baz
Error: while opening memtables error: while opening fid: 3 error: while updating skiplist error: mremap size mismatch: r
Usage:
  charm kv set KEY[@DB] VALUE [flags]

Flags:
  -h, --help   help for set

Error: while opening memtables error: while opening fid: 5 error: while updating skiplist error: mremap size mismatch: requested: 72 got: 134217728

Not really sure what's going on, but it has a strong smell of being this:

https://discuss.dgraph.io/t/error-mremap-size-mismatch-on-arm64/15333

for which a similar issue has this patch:

dgraph-io/ristretto#281

[gera]

I can confirm the same issue on and Android phone (arm64) on Termux.

[enkeyz]

Charm KV uses BadgerDB under the hood, I'd take this issue there: https://github.com/dgraph-io/badger

[idevcde]

Hi, same here, self-hosting attempt, charm version v0.12.1 and skate version v0.2.0, ARM64 (Neoverse-N1), Oracle Linux 8.6:

$ skate set key value
$ skate list
Error: while opening memtables error: while opening fid: 1 error: while updating skiplist error: mremap size mismatch: requested: 89 got: 134217728

EDIT:
I did some additional tests. It seems that the first call to the database is ok, however, next calls result in above mentioned Error. The situation is the same, no matter if self-hosted or if accessing charm.cloud.sh. I have to admit that I do not know much about BadgerDB, thus I will allow to ask, @enkeyz would you pls consider coordinating the efforts that could lead to the solution and to full operation of charm / skate ... on Arm platforms?

[dezren39]

can someone confirm this is not a charm issue? I will open a badger issue, but would prefer someone who knows the code to confirm. maybe they can update the badger db minor or something and that will help? i thought badger supported arm64.

[dezren39]

nevermind i'm not waiting another year and a half :-)

confirmed charm is using the latest version of v3, i'm not sure i'm prepared to try a major version upgrade and even if it worked locally i don't know if that's in the cards for the cloud backend. at this point, i've traced through charm/kv until it's calling db.open etc inside badger. it's likely in there, and they haven't fixed it in any v3 version. maybe v4 has a fix, or it's unpatched altogether-- despite similarities to dgraph-io/ristretto#281
and that fix got patched into badger in https://github.com/dgraph-io/badger/releases/tag/v3.2103.3

[dezren39]

in the interim since last update, this merged into ristretto:

• Disable mmap size check on arm arch as well as arm64 dgraph-io/ristretto#366

there isn't a tag for it yet, here is a ticket for the tag:

• new release dgraph-io/ristretto#374

and then also the ristretto update needs to make it into badger:

• update ristretto dgraph-io/badger#2046

this change could resolve both these issues:

• [BUG]: arm64 inconsistencies dgraph-io/badger#2027
• arm64: mremap size mismatch #32

i don't have time today, but if one wanted to manually update their fork of badger to use latest main branch of ristretto-- they could test whether this resolves right now.