From: "Garg, Shivank" <shivankg@amd.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>, Rik van Riel <riel@surriel.com>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>, Harry Yoo <harry@kernel.org>,
Jann Horn <jannh@google.com>, Lance Yang <lance.yang@linux.dev>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Zi Yan <ziy@nvidia.com>,
Matthew Brost <matthew.brost@intel.com>,
Joshua Hahn <joshua.hahnjy@gmail.com>,
Rakie Kim <rakie.kim@sk.com>, Byungchul Park <byungchul@sk.com>,
Gregory Price <gourry@gourry.net>,
Ying Huang <ying.huang@linux.alibaba.com>,
"Alistair Popple" <apopple@nvidia.com>,
Karim Manaouil <kmanaouil.dev@gmail.com>,
"Frank van der Linden" <fvdl@google.com>,
Kinsey Ho <kinseyho@google.com>, Wei Xu <weixugc@google.com>,
Bharata B Rao <bharata@amd.com>,
David Rientjes <rientjes@google.com>, Dev Jain <dev.jain@arm.com>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/6] mm: batch rmap walks during large folio migration
Date: Tue, 14 Jul 2026 11:04:37 +0530 [thread overview]
Message-ID: <442897a7-7b17-4025-bfb0-fe2db8d64198@amd.com> (raw)
In-Reply-To: <20260713190516.0c669b5207667c893a9c0938@linux-foundation.org>
On 7/14/2026 7:35 AM, Andrew Morton wrote:
> On Sun, 12 Jul 2026 07:38:46 +0000 Shivank Garg <shivankg@amd.com> wrote:
>
>> Performance:
>>
>> AMD EPYC ZEN 3, 2-socket system (1 node per socket).
>> move_pages() migrating 1 GB from node 0 -> node 1, throughput
>> in GB/s:
>> batch- batch-restore +
>> folio vanilla restore unmap restore% restore+unmap%
>> 4K 2.98±0.09 2.95±0.07 3.06±0.05 -1.0% +2.6%
>> 64K 6.16±0.09 6.24±0.08 7.80±0.08 +1.3% +26.6%
>> 256K 6.85±0.06 6.85±0.09 9.54±0.19 +0.0% +39.3%
>> 1M 7.06±0.09 7.17±0.09 9.89±0.06 +1.5% +40.1%
>> 2M 10.97±0.17 10.67±0.13 10.69±0.15 -2.7% -2.6%
>>
>> In plain migration, the folio copy itself dominate the cost, so these rmap walk
>> savings are only partly visible end-to-end.
>> When the folio copy is batched-copy and offloaded to DMA engine [1], the copy is
>> no longer the bottlneck and rmap-walk batching translates into much larger gains:
>>
>> This series + [1], DMA Offload on PTDMA (DCBM), 16 channels:
>>
>> batch-copy
>> folio vanilla -offload(dcbm) dcbm+restore dcbm+restore+unmap
>> 4K 3.36 ± 0.10 4.16 ± 0.18 4.10 ± 0.14 4.12 ± 0.13
>> 64K 6.16 ± 0.47 9.63 ± 0.23 10.00 ± 0.33 14.63 ± 0.14
>> 256K 6.70 ± 0.09 12.98 ± 0.18 13.52 ± 0.15 32.30 ± 0.65 (2.38x)
>> 1M 6.99 ± 0.02 14.32 ± 0.67 14.84 ± 0.17 38.97 ± 1.03 (2.62x)
>> 2M 10.74 ± 0.29 64.25 ± 1.48 65.36 ± 1.00 64.97 ± 1.75
>
> Well dang.
>
> Thanks. I'll await reviewer input on this series.
>
> Sashiko said things:
> https://sashiko.dev/#/patchset/20260712-migrate-rmap-batch-v1-0-872a734431d1@amd.com
Thanks Andrew.
I'm working on this and the syzbot reported issue.
Best regards,
Shivank
prev parent reply other threads:[~2026-07-14 5:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-12 7:38 [PATCH 0/6] mm: batch rmap walks during large folio migration Shivank Garg
2026-07-12 7:38 ` [PATCH 1/6] mm/rmap: Add batched version of folio_try_share_anon_rmap_pte Shivank Garg
2026-07-12 7:38 ` [PATCH 2/6] mm: factor out generic PTE batch detection from swap_pte_batch() Shivank Garg
2026-07-12 7:38 ` [PATCH 3/6] mm/migrate: split remove_migration_pte_hugetlb() out of remove_migration_pte() Shivank Garg
2026-07-12 7:38 ` [PATCH 4/6] mm/migrate: batch the restore-side migration rmap walk Shivank Garg
2026-07-12 7:38 ` [PATCH 5/6] mm/rmap: split try_to_migrate_hugetlb_one() out of try_to_migrate_one() Shivank Garg
2026-07-12 7:38 ` [PATCH 6/6] mm/rmap: batch the unmap of large folios in try_to_migrate_one() Shivank Garg
2026-07-12 18:24 ` [syzbot ci] Re: mm: batch rmap walks during large folio migration syzbot ci
2026-07-14 2:05 ` [PATCH 0/6] " Andrew Morton
2026-07-14 5:34 ` Garg, Shivank [this message]
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