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charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/13MQQ6CMBCF4auQWTum04BQV9zDsChllCZamrapG sLdrbhz+b/kfStEDpYjnKsVAmcb7eJKyEMFZtbuxmin0iCFPAkiwvjUHpMe74y+RtUxKzlq3Zo ayscHvtrX7l2G0rONaQnvnc/0XX+SlOJPyoQCSdStaiZSHTV9YmfYpaNZHjBs2/YBk6KawqwAA AA= X-Change-ID: 20260111-swap-table-p4-98ee92baa7c4 To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , Barry Song , Hugh Dickins , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Johannes Weiner , Youngjun Park , Chengming Zhou , Roman Gushchin , Shakeel Butt , Muchun Song , Qi Zheng , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Kairui Song , Yosry Ahmed , Lorenzo Stoakes , Dev Jain , Lance Yang , Michal Hocko , Michal Hocko , Qi Zheng , Lorenzo Stoakes , Yosry Ahmed X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1776364480; l=5811; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=BXHKITIYR9dCL2Vx1b1VPQ93m5+HvBPWS+sjmunJ/Dc=; 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The static metadata overhead is now close to zero, and workload performance is slightly improved. The swap cgroup static array is gone, eliminating most static swap data. For example, for mounting a 1TB swap device, this saves about 512MB of memory: Before: free -m total used free shared buff/cache available Mem: 1464 805 346 1 382 658 Swap: 1048575 0 1048575 After: free -m total used free shared buff/cache available Mem: 1464 277 899 1 356 1187 Swap: 1048575 0 1048575 Memory usage is ~512M lower, and we now have a close to 0 static overhead. It was about 2 bytes per slot before, now roughly 0.09375 bytes per slot (48 bytes ci info per cluster, which is 512 slots). Performance test is also looking good, testing Redis in a 1.5G VM using 5G ZRAM as swap: valkey-server --maxmemory 2560M redis-benchmark -r 3000000 -n 3000000 -d 1024 -c 12 -P 32 -t get Before: 3048028.953125 RPS After: 3068843.321429 RPS (0.68% better) Testing with build kernel under global pressure on a 48c96t system, limiting the total memory to 8G, using 12G ZRAM, 24 test runs, enabling THP: make -j96, using defconfig Before: user time 2904.59s system time 4773.99s After: user time 2909.38s system time 4641.55s (2.77% better) Testing with usemem on a 32c machine using 48G ramdisk and 16G RAM, 6 test run: usemem --init-time -O -y -x -n 48 1G Before: Throughput (Sum): 6011.33 MB/s Free Latency: 401097.13us After: Throughput (Sum): 6078.67 MB/s Free Latency: 390860.36us Seems similar, or slightly better. This series also reduces memory thrashing, I no longer see any: "Huh VM_FAULT_OOM leaked out to the #PF handler. Retrying PF", it was shown several times during stress testing before this series when under great pressure. Signed-off-by: Kairui Song --- Changes in v2: - Drop the RFC prefix and also the RFC part. - Now there is zero change to cgroup or refault tracking, RFC v1 changed some cgroup behavior. To archive that v2 use a standalone memcg_table for each cluster. It can be dropped or better optimized later if we have a better solution. The performance gain is partly cancelled compared to RFC v1 since we now need an extra allocation for free cluster isolation and peak memory usage is 2 bytes higher. But still looking good. That table size is accetable (1024 bytes), no RCU needed, and fits for kmalloc. Even if we keep it as it is in the future, it's still accetable. - Link to v1: https://lore.kernel.org/r/20260220-swap-table-p4-v1-0-104795d19815@tencent.com To: linux-mm@kvack.org Cc: Andrew Morton Cc: Chris Li Cc: Kairui Song Cc: Kemeng Shi Cc: Nhat Pham Cc: Baoquan He Cc: Barry Song Cc: Youngjun Park Cc: Johannes Weiner Cc: Yosry Ahmed Cc: Chengming Zhou Cc: David Hildenbrand Cc: Lorenzo Stoakes Cc: Zi Yan Cc: Baolin Wang Cc: Dev Jain Cc: Lance Yang Cc: Hugh Dickins Cc: Michal Hocko Cc: Michal Hocko Cc: Roman Gushchin Cc: Shakeel Butt Cc: Muchun Song Cc: Qi Zheng Cc: linux-kernel@vger.kernel.org Cc: cgroups@vger.kernel.org --- Kairui Song (11): mm, swap: simplify swap cache allocation helper mm, swap: move common swap cache operations into standalone helpers mm/huge_memory: move THP gfp limit helper into header mm, swap: add support for stable large allocation in swap cache directly mm, swap: unify large folio allocation mm/memcg, swap: tidy up cgroup v1 memsw swap helpers mm, swap: support flexible batch freeing of slots in different memcg mm/swap: delay and unify memcg lookup and charging for swapin mm/memcg, swap: store cgroup id in cluster table directly mm/memcg: remove no longer used swap cgroup array mm, swap: merge zeromap into swap table MAINTAINERS | 1 - include/linux/huge_mm.h | 30 +++ include/linux/memcontrol.h | 16 +- include/linux/swap.h | 19 +- include/linux/swap_cgroup.h | 47 ---- mm/Makefile | 3 - mm/huge_memory.c | 2 +- mm/internal.h | 5 - mm/memcontrol-v1.c | 66 ++++-- mm/memcontrol.c | 32 +-- mm/memory.c | 88 ++------ mm/page_io.c | 58 ++++- mm/shmem.c | 122 +++-------- mm/swap.h | 72 ++---- mm/swap_cgroup.c | 172 --------------- mm/swap_state.c | 519 +++++++++++++++++++++++++------------------- mm/swap_table.h | 134 ++++++++++-- mm/swapfile.c | 121 +++++++---- mm/vmscan.c | 2 +- mm/zswap.c | 25 +-- 20 files changed, 709 insertions(+), 825 deletions(-) --- base-commit: db2a1695b2b6feb071b47b72e61d0359bf1524bf change-id: 20260111-swap-table-p4-98ee92baa7c4 Best regards, -- Kairui Song