Re: [PATCH v1 0/4] Enable >0 order folio memory compaction

Zi Yan
2023-11-21T16:45:35Z

[-- Attachment #1: Type: text/plain, Size: 2385 bytes --]

On 21 Nov 2023, at 10:46, Ryan Roberts wrote:

>>
>> vm-scalability results
>> ===
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
>>
>> commit:
>> 6.6.0-rc4-mm-everything-2023-10-21-02-40+
>> 6.6.0-rc4-split-folio-in-compaction+
>> 6.6.0-rc4-folio-migration-in-compaction+
>> 6.6.0-rc4-folio-migration-free-page-split+
>> 6.6.0-rc4-folio-migration-free-page-split-sort-src+
>>
>> 6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
>> ---------------- --------------------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \ | \
>> 12896955 +2.7% 13249322 -4.0% 12385175 ± 5% +1.1% 13033951 -0.4% 12845698 vm-scalability.throughput
>
> Hi Zi,
>
> Are you able to add any commentary to these results as I'm struggling to
> interpret them; Is a positive or negative change better (are they times or
> rates?). What are the stddev values? The title suggests percent but the values
> are huge - I'm trying to understand what the error bars look like - are the
> swings real or noise?

The metric is vm-scalability.throughput, so the larger the better. Some %stddev
are not present since they are too small. For 6.6.0-rc4-folio-migration-in-compaction+,
%stddev is greater than %change, so the change might be noise.

Also, I talked to DavidH in last THP Cabal meeting about this. He suggested that
there are a lot of noise in vm-scalability like what I have here and I should
run more iterations and on bare metal. I am currently rerun them on a baremetal
and more iterations on the existing VM and report the results later. Please
note that the runs really take some time.

In addition, I will find other fragmentation-related benchmarks, so we can see
the impact on memory fragmentation.

--
Best Regards,
Yan, Zi

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 854 bytes --]