Re: [RFC PATCH 0/5] slub: Delay freezing of CPU partial slabs

Hyeonggon Yoo
2023-10-18T06:34:30Z

On Wed, Oct 18, 2023 at 12:45 AM <chengming.zhou@linux.dev> wrote:
> 4. Testing
> ==========
> We just did some simple testing on a server with 128 CPUs (2 nodes) to
> compare performance for now.
>
> - perf bench sched messaging -g 5 -t -l 100000
> baseline RFC
> 7.042s 6.966s
> 7.022s 7.045s
> 7.054s 6.985s
>
> - stress-ng --rawpkt 128 --rawpkt-ops 100000000
> baseline RFC
> 2.42s 2.15s
> 2.45s 2.16s
> 2.44s 2.17s
>
> It shows above there is about 10% improvement on stress-ng rawpkt
> testcase, although no much improvement on perf sched bench testcase.
>
> Thanks for any comment and code review!

Hi Chengming, this is the kerneltesting.org test report for your patch series.

I applied this series on my slab-experimental tree [1] for testing,
and I observed several kernel panics [2] [3] [4] on kernels without
CONFIG_SLUB_CPU_PARTIAL.

To verify that this series caused kernel panics, I tested before and after
applying it on Vlastimil's slab/for-next and yeah, this series was the cause.

System is deadlocked on memory and the OOM-killer says there is a
huge amount of slab memory. So maybe there is a memory leak or it makes
slab memory grow unboundedly?

[1] https://git.kerneltesting.org/slab-experimental/
[2] https://lava.kerneltesting.org/scheduler/job/127#bottom
[3] https://lava.kerneltesting.org/scheduler/job/131#bottom
[4] https://lava.kerneltesting.org/scheduler/job/134#bottom

>
> Chengming Zhou (5):
> slub: Introduce on_partial()
> slub: Don't manipulate slab list when used by cpu
> slub: Optimize deactivate_slab()
> slub: Don't freeze slabs for cpu partial
> slub: Introduce get_cpu_partial()
>
> mm/slab.h | 2 +-
> mm/slub.c | 257 +++++++++++++++++++++++++++++++-----------------------
> 2 files changed, 150 insertions(+), 109 deletions(-)
>
> --
> 2.40.1
>