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J . Mercier" , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 9650B1C000B X-Stat-Signature: 5a6qqpx3hzqqastgbnruxourxn5fdp4s X-Rspam-User: X-HE-Tag: 1714466056-619459 X-HE-Meta: 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 UwGuUA0d EymLrFTMWtJIBDZl4+js4g1/hm0e453un9sgish/EqHa3HDQtEkHTcziW9B6PILmlSCuO9+0q3RUzkph5B3icAVfL+o/EYLe8BU2MXU1itj5ii8iTRZXtbibZomf+A+5FthfxkhW4QvThtYWJxLqIb5eCtWR6LUhjWyil6jErUTf/A2TmOyETzKsLHm+z6sogpw3MmQA96yQgmgJUQHQt0Z1QCD6xe2eE/D0zgV13gagE2jX4Nytx6eMUK1d/cuL7p5Qd8m80e9pdm3YlFUtA+b74cUqUFhydWEq+G8VjJnfydSC/jeYzRNO6Qol+LO61sa9hNuuVbWLI93E= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 29, 2024 at 11:06=E2=80=AFPM Shakeel Butt wrote: > > mem_cgroup_events_index is a translation table to get the right index of > the memcg relevant entry for the general vm_event_item. At the moment, > it is defined as integer array. However on a typical system the max > entry of vm_event_item (NR_VM_EVENT_ITEMS) is 113, so we don't need to > use int as storage type of the array. For now just use int8_t as type > and add a BUILD_BUG_ON() and will switch to short once NR_VM_EVENT_ITEMS > touches 127. > > Another benefit of this change is that the translation table fits in 2 > cachelines while previously it would require 8 cachelines (assuming 64 > bytes cachesline). > > Signed-off-by: Shakeel Butt > Reviewed-by: Roman Gushchin Reviewed-by: Yosry Ahmed > --- > Changes since v2: > - Used S8_MAX instead of 127 > - Update commit message based on Yosry's feedback. > > mm/memcontrol.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 602ad5faad4d..c146187cda9c 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -607,11 +607,13 @@ static const unsigned int memcg_vm_event_stat[] =3D= { > }; > > #define NR_MEMCG_EVENTS ARRAY_SIZE(memcg_vm_event_stat) > -static int mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly; > +static int8_t mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly; > > static void init_memcg_events(void) > { > - int i; > + int8_t i; > + > + BUILD_BUG_ON(NR_VM_EVENT_ITEMS >=3D S8_MAX); > > for (i =3D 0; i < NR_MEMCG_EVENTS; ++i) > mem_cgroup_events_index[memcg_vm_event_stat[i]] =3D i + 1= ; > -- > 2.43.0 >