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b=brJP1+z26wVKIZMVtWGv/VObdgbyW/nl5Ryl8E1JWdUv+s2XaZjH/yZxbMdIkpAE/ vExncNyidXnpQz5I4ou62AkWSsUcC5ChMDID0fXSk91IYIVfhwaE6Vp6viAt14EWYH fP0o1P1rhEZDV4eSUcYD0p5s0zT7Q/4IC8C761st0z7Ybc9HIszJuIjNvH04cCoCJp IfymBV1DwHyojOEaHlFGZ2inIDBlbqyv+KvnkQAbj5zCS2BQI2T3/sqwGUEEZkzgeV ceRTeF/+edGXHQP7zqyQ93mpQmtIidZwJWsH4RwraNfpz5vjq6F2k7+RnWvbaJBmmZ lR0n580s61n0g== Message-ID: <308c809e-160a-4829-a8b9-9c7682fcd251@kernel.org> Date: Thu, 4 Dec 2025 13:42:18 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH -next v2] mm: vmscan: correct nr_requested tracing in scan_folios To: Chen Ridong , akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org, mhocko@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, yuzhao@google.com, jaewon31.kim@samsung.com, ioworker0@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com, chenridong@huawei.com References: <20251204122355.1822919-1-chenridong@huaweicloud.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251204122355.1822919-1-chenridong@huaweicloud.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 7EB171A000E X-Stat-Signature: n4765exbq1c4hhehw8a8yosigecypu6r X-Rspam-User: X-HE-Tag: 1764852145-122954 X-HE-Meta: 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 fzATrJII gc2gsSSmsCn10zupGPaRRELzuaH8tN+ESgwILj0TaNYOmqv36g14uKZcfj0G65cHWV/yvpyS4sDZVx99+Ikg0Wn7lDK9akOTHfBB/F12UFqFa/ODtGsVrRGMau38uNJMZWqXtUrsRcHXIyR9dIrtcB0/S4x51QMDB7c75OFyN1K1/k7r/ks4P4hyeAeG5SljDmaEsnfyvIstckmkJDnXq1s7S7NYzR0elJBNIt1MnRcafdeY6bwO5b/8q/DQ/C+i1C899uywXi6Kv9xYRh7UAq3JUpSiXEk4UnjEzhDxu5jA3i7ksStD0aUs4x+eFltGxojHweTpoE+3J2JJu76qqTaxhr82e5mk92F7E 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 12/4/25 13:23, Chen Ridong wrote: > From: Chen Ridong > > When enabling vmscan tracing, it is observed that nr_requested is always > 4096, which is confusing. > > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ... > > This is because it prints MAX_LRU_BATCH, which is meaningless as it's a > constant. To fix this, modify it to print capped valued. > > Fixes: 8c2214fc9a47 ("mm: multi-gen LRU: reuse some legacy trace events") > Signed-off-by: Chen Ridong > --- > mm/vmscan.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 584f41eb4c14..a0a74cac947b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -4404,7 +4404,8 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, > int scanned = 0; > int isolated = 0; > int skipped = 0; > - int remaining = min(nr_to_scan, MAX_LRU_BATCH); > + int scan_batch = min(nr_to_scan, MAX_LRU_BATCH); > + int remaining = scan_batch; > struct lru_gen_folio *lrugen = &lruvec->lrugen; > struct mem_cgroup *memcg = lruvec_memcg(lruvec); > > @@ -4464,7 +4465,7 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, > count_memcg_events(memcg, item, isolated); > count_memcg_events(memcg, PGREFILL, sorted); > __count_vm_events(PGSCAN_ANON + type, isolated); > - trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, MAX_LRU_BATCH, > + trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, scan_batch, > scanned, skipped, isolated, > type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON); > if (type == LRU_GEN_FILE) Acked-by: David Hildenbrand (Red Hat) -- Cheers David