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To: laoar.shao@gmail.com,ast@kernel.org,daniel@iogearbox.net,andrii@kernel.org,eddyz87@gmail.com,memxor@gmail.com,mingo@redhat.com,peterz@infradead.org,juri.lelli@redhat.com,vincent.guittot@linaro.org,akpm@linux-foundation.org,david@kernel.org,gourry@gourry.net,tj@kernel.org,hannes@cmpxchg.org,mkoutny@suse.com,shakeel.butt@linux.dev,roman.gushchin@linux.dev,yu.c.chen@intel.com,zhao1.liu@intel.com,tim.c.chen@linux.intel.com,lizhe.67@bytedance.com
Cc: bpf@vger.kernel.org,linux-mm@kvack.org,cgroups@vger.kernel.org,linux-kernel@vger.kernel.org,laoar.shao@gmail.com,ast@kernel.org,andrii@kernel.org,daniel@iogearbox.net,martin.lau@kernel.org,eddyz87@gmail.com,yonghong.song@linux.dev,mason@kernel.org,ihor.solodrai@linux.dev
Subject: Re: [RFC PATCH v3 bpf-next 3/5] sched: add helpers for numa balancing
Date: Mon, 19 Oct 2026 07:14:36 +0000 (UTC) [thread overview]
Message-ID: <03f6cc15036fbecfd577d878d80d7b182b1cc6574e8bb7daabf6ad8e44fd59dd@mail.kernel.org> (raw)
In-Reply-To: <20261019064157.29885-4-laoar.shao@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2044 bytes --]
> sched: add helpers for numa balancing
TL;DR: Nits only: redundant parentheses around the new numab_in_tiering_mode()
helper calls in should_numa_migrate_memory() and migrate_misplaced_folio()
could be dropped.
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 71dc47d6114d..066818498c76 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
[ ... ]
> @@ -2963,8 +2965,8 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
> this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
> last_cpupid = folio_xchg_last_cpupid(folio, this_cpupid);
>
> - if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
> - !node_is_toptier(src_nid) && !cpupid_valid(last_cpupid))
> + if (!(numab_in_tiering_mode()) && !node_is_toptier(src_nid) &&
> + !cpupid_valid(last_cpupid))
> return false;
this isn't a bug, but could the extra parentheses in
!(numab_in_tiering_mode()) be dropped here? They were needed around the
old bitwise test, and the other converted sites such as
task_numa_fault() call the helper without them.
[ ... ]
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 15b45832bcfa..a622df9a9b42 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
[ ... ]
> @@ -2770,7 +2771,7 @@ int migrate_misplaced_folio(struct folio *folio, int node)
> if (nr_succeeded) {
> count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
> count_memcg_events(memcg, NUMA_PAGE_MIGRATE, nr_succeeded);
> - if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
> + if ((numab_in_tiering_mode())
> && !node_is_toptier(folio_nid(folio))
> && node_is_toptier(node))
> mod_lruvec_state(lruvec, PGPROMOTE_SUCCESS, nr_succeeded);
The same applies to the parentheses in
if ((numab_in_tiering_mode()) here.
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/39213018427
next prev parent reply other threads:[~2026-10-19 7:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-19 6:41 [RFC PATCH v3 bpf-next 0/5] BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 1/5] sched: fix stale get_pref_llc() stub for !CONFIG_SCHED_CACHE Yafang Shao
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 2/5] sched: use static_branch_likely() for the NUMA balancing tick check Yafang Shao
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 3/5] sched: add helpers for numa balancing Yafang Shao
2026-10-19 7:14 ` bot+bpf-ci [this message]
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 4/5] sched: add BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-10-19 7:24 ` bot+bpf-ci
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 5/5] selftests/bpf: add tests for the numab kfuncs Yafang Shao
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