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AJvYcCU82Ifw9RRH5/m8owJyhWdc9M7QN/H81nJF14iIQ6/FFRK2Acm8sZOWqArfn6lR5n0zjyU0iwOgbE44sXp8+nawe1A= X-Gm-Message-State: AOJu0YxAgjFEdvxWSkNUfEteg9Kom+71MVzIl1TuDMM2Cyyl99fnlpvw dvjCxEyw1vtldqKqUBcclOmIQD5Uedh1F7U8qE1/+Fg7yQek/pSTaOMWFRmLmLbPD0Qk5+s0FB6 AYpXt83T3EeTy7zLSqOFvCj8wZi7kvGeYFOep X-Google-Smtp-Source: AGHT+IGA4OCcGROuejRidml9TPv3K1lykvce1DRnVEz/IoowhfwrU1qPRaqaxWUMBc5Cjk0KUTlQ2N0VCZ1aAbsKciE= X-Received: by 2002:a17:906:b351:b0:a59:674:a297 with SMTP id cd17-20020a170906b35100b00a590674a297mr692168ejb.64.1714518462865; Tue, 30 Apr 2024 16:07:42 -0700 (PDT) MIME-Version: 1.0 References: <20240430060612.2171650-1-shakeel.butt@linux.dev> <20240430060612.2171650-5-shakeel.butt@linux.dev> In-Reply-To: From: Yosry Ahmed Date: Tue, 30 Apr 2024 16:07:05 -0700 Message-ID: Subject: Re: [PATCH v3 4/8] memcg: reduce memory for the lruvec and memcg stats To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , "T . 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-Stat-Signature: dzqeacaqjjkt37tpzqtmoqcnpe4bbxfn X-Rspamd-Queue-Id: 9708220023 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1714518464-172027 X-HE-Meta: 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 3hP9WwaG 4Qp6mNbTtQWWWrCfH2FCb3MLFy6USPHa5zIy6bpUlqrvhXdOimT7fB9vomWqo1po9AVZ8/vLSv2LRwePfFA0Bo4a2LKLvBaus/Pb6VbvSocE41V1gbVVhSrZXeBEFEVmHA8CaRj7+0DYdWA+BL+WKrf4HghaYpNiuXyGXBlFlgB6YNtw3bHgv7tIQYF/MEOcFWaBAFAgVGRPowpAxCdjpxCKjnYj24a5bUWu/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.009230, 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 Tue, Apr 30, 2024 at 4:00=E2=80=AFPM Shakeel Butt wrote: > > On Tue, Apr 30, 2024 at 10:41:01AM -0700, Yosry Ahmed wrote: > > On Tue, Apr 30, 2024 at 10:38=E2=80=AFAM Shakeel Butt wrote: > > > > > > On Tue, Apr 30, 2024 at 01:41:38AM -0700, Yosry Ahmed wrote: > > > > On Mon, Apr 29, 2024 at 11:06=E2=80=AFPM Shakeel Butt wrote: > > > > > > > > [...] > > > > > + > > > > > +#define NR_MEMCG_NODE_STAT_ITEMS ARRAY_SIZE(memcg_node_stat_item= s) > > > > > +#define NR_MEMCG_STATS (NR_MEMCG_NODE_STAT_ITEMS + ARRAY_SIZE(me= mcg_stat_items)) > > > > > +static int8_t mem_cgroup_stats_index[MEMCG_NR_STAT] __read_mostl= y; > > > > > > > > NR_MEMCG_STATS and MEMCG_NR_STAT are awfully close and have differe= nt > > > > meanings. I think we should come up with better names (sorry nothin= g > > > > comes to mind) or add a comment to make the difference more obvious= . > > > > > > > > > > How about the following comment? > > > > The comment LGTM. I prefer renaming them though if someone can come up > > with better names. > > > > I will be posting v4 and will change the name (still thinking about the > name) becasuse: > > > > > > +static void init_memcg_stats(void) > > > > > +{ > > > > > + int8_t i, j =3D 0; > > > > > + > > > > > + /* Switch to short once this failure occurs. */ > > > > > + BUILD_BUG_ON(NR_MEMCG_STATS >=3D 127 /* INT8_MAX */); > > The above should be MEMCG_NR_STAT instead of NR_MEMCG_STATS. Yeah it's pretty confusing :) How about something explicit like: NR_MEMCG_POSSIBLE_STAT_ITEMS / MEMCG_MAX_STAT_ITEM NR_MEMCG_ACTUAL_STAT_ITEMS / MEMCG_ACTUAL_NR_STAT They look ugly, but I can't think of anything better. Maybe they will inspire something better :)