From: Gregory Price <gourry@gourry.net>
To: Zi Yan <ziy@nvidia.com>
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Subject: Re: [PATCH v2 0/4] sched/numa: stop VMA scan filters from gating promotion
Date: Fri, 18 Sep 2026 17:42:20 -0400 [thread overview]
Message-ID: <aq2s9R9I-Y9D3tx_@gourry-fedora-PF4VCD3F> (raw)
In-Reply-To: <DLIQQNUL2RTD.IGN8MYHYMW1E@nvidia.com>
On Fri, Sep 18, 2026 at 04:56:34PM -0400, Zi Yan wrote:
> >
> > Tested on a host with 768GB/256GB DRAM/CXL.
> > Ran 2 ~430GB database workloads with large (>300GB) shmem VMAs.
>
> Do you just launch them without any additional NUMA control or NUMA
> policy configuration, like using numactl? Just want to understand the
> scope of the issue and how well the fixes are tested. It might be good
> to have a list of expected behaviors for people/AI to check against.
>
We found these issues while testing fairness controls with Joshua's
tiered memcg limits patches [1].
We were seeing very lopsided bandwidth utilization between tiers.
When dropped all the memcg extensions and tested these patches by
themselves, we found that numa balancing was completely broken -
starting with Johannes' shmem fix [2].
Otherwise - No other numa controls are used on these workloads.
- no numactl
- no mbind()/set_mempolicy()
- no cpuset.mems
- etc
These fixes impact the fault-injecting side (spraying PROT_NONE),
not the fault-handling side. So mempolicy and cpuset doesn't really
come into the picture.
It's more of an internal-consistency issue for numab itself.
~Gregory
[1] https://lore.kernel.org/all/20260807202059.2620949-1-joshua.hahnjy@gmail.com/
[2] https://lore.kernel.org/all/20260629163337.1264881-1-hannes@cmpxchg.org/
prev parent reply other threads:[~2026-09-18 21:42 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 0:18 [PATCH v2 0/4] sched/numa: stop VMA scan filters from gating promotion Gregory Price
2026-09-11 0:18 ` [PATCH v2 1/4] mm: support promotion-only NUMA hinting scans Gregory Price
2026-09-17 16:03 ` Peter Zijlstra
2026-09-17 16:14 ` Gregory Price
2026-09-18 12:26 ` David Hildenbrand (Arm)
2026-09-18 12:37 ` David Hildenbrand (Arm)
2026-09-18 13:46 ` Gregory Price
2026-09-18 13:56 ` David Hildenbrand (Arm)
2026-09-11 0:18 ` [PATCH v2 2/4] mm: allow shared folios to be promoted to a fast tier Gregory Price
2026-09-17 16:08 ` Peter Zijlstra
2026-09-17 16:18 ` Gregory Price
2026-09-17 16:23 ` Peter Zijlstra
2026-09-17 16:39 ` Gregory Price
2026-09-18 4:14 ` Bharata B Rao
2026-09-17 17:49 ` Zi Yan
2026-09-18 12:54 ` David Hildenbrand (Arm)
2026-09-18 12:53 ` David Hildenbrand (Arm)
2026-09-18 13:54 ` Gregory Price
2026-09-18 13:57 ` David Hildenbrand (Arm)
2026-09-11 0:18 ` [PATCH v2 3/4] sched/numa: scan read-only file mappings in tiering mode Gregory Price
2026-09-18 12:58 ` David Hildenbrand (Arm)
2026-09-18 13:57 ` Gregory Price
2026-09-18 13:59 ` David Hildenbrand (Arm)
2026-09-18 14:53 ` Lorenzo Stoakes (ARM)
2026-09-18 15:48 ` Gregory Price
2026-09-18 16:19 ` Lorenzo Stoakes (ARM)
2026-09-18 16:38 ` Gregory Price
2026-09-11 0:18 ` [PATCH v2 4/4] sched/numa: do not let VMA PID activity gate promotion Gregory Price
2026-09-17 16:19 ` Peter Zijlstra
2026-09-18 13:01 ` David Hildenbrand (Arm)
2026-09-18 13:59 ` Gregory Price
2026-09-11 5:38 ` [PATCH v2 0/4] sched/numa: stop VMA scan filters from gating promotion Gregory Price
2026-09-17 5:35 ` Andrew Morton
2026-09-17 6:59 ` Gregory Price
2026-09-17 15:53 ` David Hildenbrand (Arm)
2026-09-18 20:56 ` Zi Yan
2026-09-18 21:42 ` Gregory Price [this message]
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