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b=dvoF5wYzcFG9Nrl6nny3ed0swGUNu7wEsqqlI6jaIUZ7UWokOtEe8tpEM+cpYYl93 Xemi+o08AjNxxBWzRTXO8FxLzzbJcxrmrBAQ7hzud0ySVzUUTWkQ3FxH51A5hoGq66 7RAm5R+RIHBCDYyxiMAvhH8luvUhtQgG80KgBZgQrl9oZrKXyODkFpiXsVHYVWduDy vg3qArNHOBTeQF0i0Dr1UyNuiBv6bLAprg06d5dS97krGEb6+oYVMM5Iv26mzleYNj REs0jtz7dg0TP55oRyGCgkm9/67SYd/Iwi2MJKm6VKEjAR/3yNoBOfUJKyo6rIg1Pb Q3hgOnOUcWYnQ== Received: by mail-yw1-f174.google.com with SMTP id 00721157ae682-723ad237d1eso3743817b3.1 for ; Tue, 02 Sep 2025 05:18:08 -0700 (PDT) X-Gm-Message-State: AOJu0YyCZlwBAWdd6wRzkMfSznDL5XW2p2ksZisD3Fn4TNioFM5aqnZq FO8fV59gO/Pw8wLCkbAeTt5wvoFHVLyZpIlqnXdLpTEOJPzHHhGcl3tkkfDjP6YFI6f4SnuOlp4 k1WAal4J05kh+bFsmzf1U0R0nuC4UQRDi2wvABSyqGw== X-Google-Smtp-Source: AGHT+IF/fv8Z/lXj5JP5clHJ8aYfTcZOW+8f7Hi0XMCpJtw1fdJZ8y33yDnQyUMOboAz/G8jvSnLVwL7BHJdmVDe/zg= X-Received: by 2002:a05:690c:6c8f:b0:722:731d:f622 with SMTP id 00721157ae682-7227636c98cmr110511477b3.17.1756815487736; Tue, 02 Sep 2025 05:18:07 -0700 (PDT) MIME-Version: 1.0 References: <20250806161748.76651-1-ryncsn@gmail.com> <20250806161748.76651-3-ryncsn@gmail.com> In-Reply-To: <20250806161748.76651-3-ryncsn@gmail.com> From: Chris Li Date: Tue, 2 Sep 2025 05:17:56 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: Ac12FXwYM-QjowMD2uLpV6vp34CLhFUBAr49slLfUGLs_PraM_RMeUsbnnKX7LE Message-ID: Subject: Re: [PATCH v2 2/3] mm, swap: remove fragment clusters counter To: Kairui Song Cc: linux-mm@kvack.org, Andrew Morton , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , "Huang, Ying" , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: B36C98000C X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: wbjp67q1e3149zynbfogjy8c77kypyax X-HE-Tag: 1756815489-83654 X-HE-Meta: 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 I1WjNrb0 7zM4Wo7eufmTbcedAvWpiQhLyW9eakJuqdVgp/HG275wx4h8vqaKR+rt/GasFnj9TDMt9K2VFWHb73zQ3QWc+VIBAg5VRlnKe480ANI8a6d2Z5AHn1q3PR6o1UJRvoya+cIMcKiXPoYJ2ZVYmA8wyiuKYLM+9RHrXH4VMngcH5h9uH0tyalsLGjTUoBI6o8NyVbgegf76VfXReW0GjwWX/P+d/slxIaO28pCJjX4MSNW38MWwCMMsXAizeaePbm4HR9fn+w10laLZKSO5bjuFHBMT5g3isgvtNDq1XrOesUBNwBy+g2FzreHk1RF5EGnXUDW1W0wCe/wFk52pzfQ/taBXxD/8Au+oDIn5 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: Acked-by: Chris Li Chris On Wed, Aug 6, 2025 at 9:18=E2=80=AFAM Kairui Song wrote= : > > From: Kairui Song > > It was used for calculating the iteration number when the swap allocator > wants to scan the whole fragment list. Now the allocator only scans one > fragment cluster at a time, so no one uses this counter anymore. > > Remove it as a cleanup; the performance change is marginal: > > Build linux kernel using 10G ZRAM, make -j96, defconfig with 2G cgroup > memory limit, on top of tmpfs, 64kB mTHP enabled: > > Before: sys time: 6278.45s > After: sys time: 6176.34s > > Change to 8G ZRAM: > > Before: sys time: 5572.85s > After: sys time: 5531.49s > > Signed-off-by: Kairui Song > --- > include/linux/swap.h | 1 - > mm/swapfile.c | 7 ------- > 2 files changed, 8 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 2fe6ed2cc3fd..a060d102e0d1 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -310,7 +310,6 @@ struct swap_info_struct { > /* list of cluster that contains = at least one free slot */ > struct list_head frag_clusters[SWAP_NR_ORDERS]; > /* list of cluster that are fragm= ented or contented */ > - atomic_long_t frag_cluster_nr[SWAP_NR_ORDERS]; > unsigned int pages; /* total of usable pages of swap = */ > atomic_long_t inuse_pages; /* number of those currently in u= se */ > struct swap_sequential_cluster *global_cluster; /* Use one global= cluster for rotating device */ > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 1f1110e37f68..5fdb3cb2b8b7 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -470,11 +470,6 @@ static void move_cluster(struct swap_info_struct *si= , > else > list_move_tail(&ci->list, list); > spin_unlock(&si->lock); > - > - if (ci->flags =3D=3D CLUSTER_FLAG_FRAG) > - atomic_long_dec(&si->frag_cluster_nr[ci->order]); > - else if (new_flags =3D=3D CLUSTER_FLAG_FRAG) > - atomic_long_inc(&si->frag_cluster_nr[ci->order]); > ci->flags =3D new_flags; > } > > @@ -965,7 +960,6 @@ static unsigned long cluster_alloc_swap_entry(struct = swap_info_struct *si, int o > * allocation, but reclaim may drop si->lock and race wit= h another user. > */ > while ((ci =3D isolate_lock_cluster(si, &si->frag_cluster= s[o]))) { > - atomic_long_dec(&si->frag_cluster_nr[o]); > found =3D alloc_swap_scan_cluster(si, ci, cluster= _offset(si, ci), > 0, usage); > if (found) > @@ -3217,7 +3211,6 @@ static struct swap_cluster_info *setup_clusters(str= uct swap_info_struct *si, > for (i =3D 0; i < SWAP_NR_ORDERS; i++) { > INIT_LIST_HEAD(&si->nonfull_clusters[i]); > INIT_LIST_HEAD(&si->frag_clusters[i]); > - atomic_long_set(&si->frag_cluster_nr[i], 0); > } > > /* > -- > 2.50.1 >