v1->v2: -Send cleanup to wq_monitor.py separately. -Add patch to avoid use after free of bdi. -Rename wb_calc_cg_thresh to cgwb_calc_thresh as Tejun suggested. -Use rcu walk to avoid use after free. -Add debug output to each related patches. This series tries to improve visilibity of writeback. Patch 1 make /sys/kernel/debug/bdi/xxx/stats show writeback info of whole bdi instead of only writeback info in root cgroup. Patch 2 add a new debug file /sys/kernel/debug/bdi/xxx/wb_stats to show per wb writeback info. Patch 4 add wb_monitor.py to monitor basic writeback info of running system, more info could be added on demand. Rest patches are some random cleanups. More details can be found in respective patches. Thanks! This series is on top of patchset [1]. [1] https://lore.kernel.org/lkml/20240123183332.876854-1-shikemeng@xxxxxxxxxxxxxxx/T/#mc6455784a63d0f8aa1a2f5aff325abcdf9336b76 Following domain hierarchy is tested: global domain (320G) / \ cgroup domain1(10G) cgroup domain2(10G) | | bdi wb1 wb2 /* all writeback info of bdi is successfully collected */ # cat /sys/kernel/debug/bdi/252:16/stats: BdiWriteback: 448 kB BdiReclaimable: 1303904 kB BdiDirtyThresh: 189914124 kB DirtyThresh: 195337564 kB BackgroundThresh: 32516508 kB BdiDirtied: 3591392 kB BdiWritten: 2287488 kB BdiWriteBandwidth: 322248 kBps b_dirty: 0 b_io: 0 b_more_io: 2 b_dirty_time: 0 bdi_list: 1 state: 1 /* per wb writeback info is collected */ # cat /sys/kernel/debug/bdi/252:16/wb_stats: cat wb_stats WbCgIno: 1 WbWriteback: 0 kB WbReclaimable: 0 kB WbDirtyThresh: 0 kB WbDirtied: 0 kB WbWritten: 0 kB WbWriteBandwidth: 102400 kBps b_dirty: 0 b_io: 0 b_more_io: 0 b_dirty_time: 0 state: 1 WbCgIno: 4284 WbWriteback: 448 kB WbReclaimable: 818944 kB WbDirtyThresh: 3096524 kB WbDirtied: 2266880 kB WbWritten: 1447936 kB WbWriteBandwidth: 214036 kBps b_dirty: 0 b_io: 0 b_more_io: 1 b_dirty_time: 0 state: 5 WbCgIno: 4325 WbWriteback: 224 kB WbReclaimable: 819392 kB WbDirtyThresh: 2920088 kB WbDirtied: 2551808 kB WbWritten: 1732416 kB WbWriteBandwidth: 201832 kBps b_dirty: 0 b_io: 0 b_more_io: 1 b_dirty_time: 0 state: 5 /* monitor writeback info */ # ./wb_monitor.py 252:16 -c writeback reclaimable dirtied written avg_bw 252:16_1 0 0 0 0 102400 252:16_4284 672 820064 9230368 8410304 685612 252:16_4325 896 819840 10491264 9671648 652348 252:16 1568 1639904 19721632 18081952 1440360 writeback reclaimable dirtied written avg_bw 252:16_1 0 0 0 0 102400 252:16_4284 672 820064 9230368 8410304 685612 252:16_4325 896 819840 10491264 9671648 652348 252:16 1568 1639904 19721632 18081952 1440360 ... Kemeng Shi (6): writeback: protect race between bdi release and bdi_debug_stats_show writeback: collect stats of all wb of bdi in bdi_debug_stats_show writeback: support retrieving per group debug writeback stats of bdi writeback: add wb_monitor.py script to monitor writeback info on bdi writeback: rename nr_reclaimable to nr_dirty in balance_dirty_pages writeback: define GDTC_INIT_NO_WB to null include/linux/writeback.h | 1 + mm/backing-dev.c | 203 ++++++++++++++++++++++++++++++---- mm/page-writeback.c | 31 ++++-- tools/writeback/wb_monitor.py | 172 ++++++++++++++++++++++++++++ 4 files changed, 378 insertions(+), 29 deletions(-) create mode 100644 tools/writeback/wb_monitor.py -- 2.30.0
