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t=1791877104; bh=DcuYY3+mv/Ns6uvfacyrd4dBgpfSbyMtyecX3H4y2hE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DlB0kj8gOlFNSD84BZwMWb5ZbV2oXW4IaLaFGcapmHBAUuLC7zPJAEShEflW7d90Z 2ITF8SGCDnhIDxAHfjDEwEtAvXceuwSpN5Fasml6JY9Wn9huixCPCLyT3uZ+1AsP/f QOGdh8bpPL2f7KQEgdkMQFTpJg+d/VB0ZERes3AU7EeweYpj1IPdrZRVasXloHdV2K FjdS4eNfe0CbiVGPsgPqkqk1Hc6oPE4Il1DhEwPDaQ3vfenYbgtC509EdQiZhRvTGK ukmwwkNFOwzqRryAIPa6FUnK5PNz4426a8gtHsmxyZGUcdlQo01a/ZMlDCQP2iOTA7 O7NL/VpOcZOZA== Message-ID: <96324eec-d307-4bbf-975e-3c9b3dd5e190@kernel.org> Date: Tue, 13 Oct 2026 09:38:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 1/3] sched: add helpers for numa balancing To: Yafang Shao , 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, 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 Cc: bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261012120438.52849-1-laoar.shao@gmail.com> <20261012120438.52849-2-laoar.shao@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: EC41D18000B X-Stat-Signature: piikkizbsotbbhz3j3ups9t31rwji37w X-HE-Tag: 1791877105-431630 X-HE-Meta: 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 pTSxDemt M8y1B/0yjAvuFDaYjH+Jz1EW2wD+H0/gk8wcpfSyWFh+Cmy2OQ/ebfp+W/m7tZJFzawY2hM6VKIV214mK7X3L6sIcnB1V/tLgwu54OT0Hd1rTSTvWVeCWNNw6TqWvPpnPVWGbPySzJIw2fsri2yrt0M1UWE1f2z85xlT1e9e6h3z1MHcUlkXI7c/Fsl3Gft3Y/lVqZ4wYmEr4lg9VBUndIj5TzeQcAJ3oZT9d+x+6G0hcroCgTvlW48NlPH8BnK8X3zsvRnlRgltXbi8cfvcByUUo8IHSgFdPm7PTbIuBw7TjmfybbAij6LqSGpQjD5bFrEDAL28bMCvo40L0f05aUAXzVjrVgmfaTVY36+2eBLZ+6ts= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/12/26 14:04, Yafang Shao wrote: > Two new helpers task_numab_enabled() and numab_mode_tiering() are > introduced to replace the scattered direct accesses to the > sched_numa_balancing static key and the sysctl_numa_balancing_mode > bitmask. > I'll only comment on the new exposed helpers. Some of these might make sense even without the bigger series. (obviously, minus the task change) > No functional change. > > Signed-off-by: Yafang Shao > --- > include/linux/sched/numa_balancing.h | 31 ++++++++++++++++++++++++++++ > kernel/sched/fair.c | 16 +++++++------- > kernel/sched/sched.h | 1 - > mm/memory-tiers.c | 3 ++- > mm/migrate.c | 7 ++++--- > mm/vmscan.c | 6 +++--- > 6 files changed, 48 insertions(+), 16 deletions(-) > > diff --git a/include/linux/sched/numa_balancing.h b/include/linux/sched/numa_balancing.h > index 52b22c5c396d..353772b49c5f 100644 > --- a/include/linux/sched/numa_balancing.h > +++ b/include/linux/sched/numa_balancing.h > @@ -8,6 +8,7 @@ > */ > > #include > +#include > > #define TNF_MIGRATED 0x01 > #define TNF_NO_GROUP 0x02 > @@ -32,6 +33,28 @@ extern void set_numabalancing_state(bool enabled); > extern void task_numa_free(struct task_struct *p, bool final); > bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio, > int src_nid, int dst_cpu); > + > +extern struct static_key_false sched_numa_balancing; > + > +/* > + * Whether NUMA balancing applies to @p. The @p argument is unused for > + * now: a later patch will consult a per-cgroup BPF policy with it. Talking about later patches in a function doc is ... wrong. > + */ > +static inline bool task_numab_enabled(struct task_struct *p) > +{ > + return static_branch_unlikely(&sched_numa_balancing); > +} > + > +/* > + * The global sysctl state, for the system-wide tiering machinery: this > + * reflects kernel.numa_balancing_mode only and takes no task. The latter part doesn't make a lot of sense in this documentation. > + */ > +static inline bool numab_mode_tiering(void) The function name isn't really intuitive. Should this be numab_in_tiering_mode numab_tiering_enabled or something like this. > +{ > + if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) > + return true; > + return false; return sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING; ? Both functions could directly have proper kerneldoc if we are already documenting these. > +} > #else > static inline void task_numa_fault(int last_node, int node, int pages, > int flags) > @@ -52,6 +75,14 @@ static inline bool should_numa_migrate_memory(struct task_struct *p, > { > return true; > } > +static inline bool task_numab_enabled(struct task_struct *p) > +{ > + return false; > +} > +static inline bool numab_mode_tiering(void) > +{ > + return false; > +} -- Cheers, David