Better handle memory fragmentation.

[clandmeter]

@moul and @fabled as discussed on #alpine-linux

Please enable CONFIG_COMPACTION and CONFIG_SLUB. This should prevent oom when memory gets fragmented.

[moul]

ping @aimxhaisse, is it ok for you too ?

[aimxhaisse]

Yes, LGTM.

I don't know why we haven't SLUB enabled, it seems to be the recommended default setting (maybe it's a residue from the 3.2 legacy config). I'd advocate to use these settings on all flavors since it's not a 'local' feature, but a global change we might want everywhere.

[moul]

Ok then, @QuentinPerez, can you enable CONFIG_SLUB ?

@aimxhaisse do you confirm that in our case, CONFIG_COMPACTION would be useless so we can skip it ?

[fabled]

I believe in this case CONFIG_COMPACTION is the more important option. It allows kernel to defragment physical memory to contiguous blocks when it's fragmented.

[aimxhaisse]

Yes, sorry I mis-interpreted the reference to 'huge pages' in the description of the option, I was under the impression it was specific to x86 huge-pages, but that's not the case.

LGTM for both configs.

[moul]

Both configs were updated, @QuentinPerez can you see with @aimxhaisse to start long-test runs against some of those kernels ?

[clandmeter]

@moul when will new kernels with these options be available?

[moul]

@clandmeter we will add a "beta" kernel today so you will be able to give a try In the meantime, we are running our long stability&performance tests

If our tests are successful we will replace all the existing kernels with the new ones

[moul]

We just released 2 kernels flagged as BETA:

• 3.2.34-std °32: Marvell LSP kernel + memory compaction and slub enabled
• 4.2.5-std °265: Mainline kernel + memory compaction and slub enabled

[clandmeter]

Thank a lot. I will give them a try and report if i find any issues.

[moul]

Thanks :)