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Howlett" , Vlastimil Babka , Yu Zhao , Zi Yan , Qi Zheng , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Kairui Song References: <20260826-mglru-flags-cleanup-v3-0-d9f1c75549c8@tencent.com> <20260826-mglru-flags-cleanup-v3-5-d9f1c75549c8@tencent.com> From: Ridong Chen In-Reply-To: <20260826-mglru-flags-cleanup-v3-5-d9f1c75549c8@tencent.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: u75kaj5r8f4zysw49ea5s4us318mbf4f X-Rspamd-Queue-Id: CDA12180002 X-HE-Tag: 1788083010-921547 X-HE-Meta: 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 9/qpd+vt ylvOKu1BgxMYZVaNElg5cEkuXiGpJl8pXU8UIx4gO/lm7RNVES23Lkp1nbcaidd6MkwBBLvUEHQB5KDhrxtCXIIUxPi4m1aU01FPOYAVCB3txu8FLtq0nxJdksCuB1FfvBppJhWaD6FAVdICSf9PjbUo8NOPM1TsbLkK3Ox1Q6FjymknRly55nvSU02y3Z03eDNncI/nXx2TUfuScWmkBS6uQOjEasCUSxEp4WVxbW6YJtmuHCBPGy9kzFW8cHFJbhKhu9O9CdrOqlHCeX9rfqb/aOvvlytqMy/R6FU9Hr/wkB36oq1F//xAxjHR1OosVdFcqd2WTkviX2tjIRu9uMK9GGtowqxB7gLePsXITljGUN8psAZBe2eQEVTix7UdPQkG3/gqNnjxzS10= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/26/2026 1:53 AM, Kairui Song via B4 Relay wrote: > From: Kairui Song > > read_ctrl_pos() encodes the tier range in a single "tier" parameter > via "tier % MAX_NR_TIERS" as the start and "min(tier, MAX_NR_TIERS-1)" > as the end. This is hard to follow, maintain, or extend. Tier values > 0..3 select a single tier, while tier == MAX_NR_TIERS selects the > full range. > > Replace it with explicit (tier_min, tier_max) parameters using a > closed [tier_min, tier_max] interval, and add LRU_TIER_MIN and > LRU_TIER_MAX for the tier bounds. The call sites now become > self-documenting: > > - get_tier_idx: (LRU_TIER_MIN, LRU_TIER_MIN) for the first tier, > (tier, tier) for each subsequent tier > - get_type_to_scan: (LRU_TIER_MIN, LRU_TIER_MAX) for the full range > > No functional change. > > Reviewed-by: Baolin Wang > Reviewed-by: Baoquan He > Reviewed-by: Barry Song > Signed-off-by: Kairui Song > --- > include/linux/mmzone.h | 2 ++ > mm/vmscan.c | 18 ++++++++++-------- > 2 files changed, 12 insertions(+), 8 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index c9ecf370cd9f..9b27cf53bdbc 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -492,6 +492,8 @@ enum lruvec_flags { > * folio->flags, masked by LRU_REFS_MASK. > */ > #define MAX_NR_TIERS 4U > +#define LRU_TIER_MIN 0U > +#define LRU_TIER_MAX (MAX_NR_TIERS - 1) > > #ifndef __GENERATING_BOUNDS_H > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 52ef4c3705bd..cdc2e44875da 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3198,8 +3198,8 @@ struct ctrl_pos { > int gain; > }; > > -static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain, > - struct ctrl_pos *pos) > +static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier_min, > + int tier_max, int gain, struct ctrl_pos *pos) > { > int i; > struct lru_gen_folio *lrugen = &lruvec->lrugen; > @@ -3208,7 +3208,7 @@ static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain, > pos->gain = gain; > pos->refaulted = pos->total = 0; > > - for (i = tier % MAX_NR_TIERS; i <= min(tier, MAX_NR_TIERS - 1); i++) { > + for (i = tier_min; i <= tier_max; i++) { > pos->refaulted += lrugen->avg_refaulted[type][i] + > atomic_long_read(&lrugen->refaulted[hist][type][i]); > pos->total += lrugen->avg_total[type][i] + > @@ -4809,9 +4809,9 @@ static int get_tier_idx(struct lruvec *lruvec, int type) > * This value is chosen because any other tier would have at least twice > * as many refaults as the first tier. > */ > - read_ctrl_pos(lruvec, type, 0, 2, &sp); > - for (tier = 1; tier < MAX_NR_TIERS; tier++) { > - read_ctrl_pos(lruvec, type, tier, 3, &pv); > + read_ctrl_pos(lruvec, type, LRU_TIER_MIN, LRU_TIER_MIN, 2, &sp); > + for (tier = LRU_TIER_MIN + 1; tier <= LRU_TIER_MAX; tier++) { > + read_ctrl_pos(lruvec, type, tier, tier, 3, &pv); > if (!positive_ctrl_err(&sp, &pv)) > break; > } > @@ -4832,8 +4832,10 @@ static int get_type_to_scan(struct lruvec *lruvec, int swappiness) > * Compare the sum of all tiers of anon with that of file to determine > * which type to scan. > */ > - read_ctrl_pos(lruvec, LRU_GEN_ANON, MAX_NR_TIERS, swappiness, &sp); > - read_ctrl_pos(lruvec, LRU_GEN_FILE, MAX_NR_TIERS, MAX_SWAPPINESS - swappiness, &pv); > + read_ctrl_pos(lruvec, LRU_GEN_ANON, LRU_TIER_MIN, LRU_TIER_MAX, > + swappiness, &sp); > + read_ctrl_pos(lruvec, LRU_GEN_FILE, LRU_TIER_MIN, LRU_TIER_MAX, > + MAX_SWAPPINESS - swappiness, &pv); > > return positive_ctrl_err(&sp, &pv); > } > Reviewed-by: Ridong Chen Thanks. -- Best regards Ridong