| From: Kemeng Shi <shikemeng@huaweicloud.com> |
| Subject: writeback: support retrieving per group debug writeback stats of bdi |
| Date: Tue, 23 Apr 2024 11:46:40 +0800 |
| |
| Add /sys/kernel/debug/bdi/xxx/wb_stats to show per group writeback stats |
| of bdi. |
| |
| Following domain hierarchy is tested: |
| global domain (320G) |
| / \ |
| cgroup domain1(10G) cgroup domain2(10G) |
| | | |
| bdi wb1 wb2 |
| |
| /* per wb writeback info of bdi is collected */ |
| 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: 4091 |
| WbWriteback: 1792 kB |
| WbReclaimable: 820512 kB |
| WbDirtyThresh: 6004692 kB |
| WbDirtied: 1820448 kB |
| WbWritten: 999488 kB |
| WbWriteBandwidth: 169020 kBps |
| b_dirty: 0 |
| b_io: 0 |
| b_more_io: 1 |
| b_dirty_time: 0 |
| state: 5 |
| |
| WbCgIno: 4131 |
| WbWriteback: 1120 kB |
| WbReclaimable: 820064 kB |
| WbDirtyThresh: 6004728 kB |
| WbDirtied: 1822688 kB |
| WbWritten: 1002400 kB |
| WbWriteBandwidth: 153520 kBps |
| b_dirty: 0 |
| b_io: 0 |
| b_more_io: 1 |
| b_dirty_time: 0 |
| state: 5 |
| |
| [shikemeng@huaweicloud.com: fix build problems] |
| Link: https://lkml.kernel.org/r/20240423034643.141219-4-shikemeng@huaweicloud.com |
| Link: https://lkml.kernel.org/r/20240423034643.141219-3-shikemeng@huaweicloud.com |
| Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> |
| Cc: Brian Foster <bfoster@redhat.com> |
| Cc: David Howells <dhowells@redhat.com> |
| Cc: David Sterba <dsterba@suse.com> |
| Cc: Jan Kara <jack@suse.cz> |
| Cc: Mateusz Guzik <mjguzik@gmail.com> |
| Cc: Matthew Wilcox (Oracle) <willy@infradead.org> |
| Cc: SeongJae Park <sj@kernel.org> |
| Cc: Stephen Rothwell <sfr@canb.auug.org.au> |
| Cc: Tejun Heo <tj@kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| include/linux/writeback.h | 1 |
| mm/backing-dev.c | 81 +++++++++++++++++++++++++++++++++++- |
| mm/page-writeback.c | 19 ++++++++ |
| 3 files changed, 99 insertions(+), 2 deletions(-) |
| |
| --- a/include/linux/writeback.h~writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi |
| +++ a/include/linux/writeback.h |
| @@ -355,6 +355,7 @@ int dirtytime_interval_handler(struct ct |
| |
| void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); |
| unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh); |
| +unsigned long cgwb_calc_thresh(struct bdi_writeback *wb); |
| |
| void wb_update_bandwidth(struct bdi_writeback *wb); |
| |
| --- a/mm/backing-dev.c~writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi |
| +++ a/mm/backing-dev.c |
| @@ -155,19 +155,96 @@ static int bdi_debug_stats_show(struct s |
| } |
| DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats); |
| |
| +static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb, |
| + struct wb_stats *stats) |
| +{ |
| + |
| + seq_printf(m, |
| + "WbCgIno: %10lu\n" |
| + "WbWriteback: %10lu kB\n" |
| + "WbReclaimable: %10lu kB\n" |
| + "WbDirtyThresh: %10lu kB\n" |
| + "WbDirtied: %10lu kB\n" |
| + "WbWritten: %10lu kB\n" |
| + "WbWriteBandwidth: %10lu kBps\n" |
| + "b_dirty: %10lu\n" |
| + "b_io: %10lu\n" |
| + "b_more_io: %10lu\n" |
| + "b_dirty_time: %10lu\n" |
| + "state: %10lx\n\n", |
| +#ifdef CONFIG_CGROUP_WRITEBACK |
| + cgroup_ino(wb->memcg_css->cgroup), |
| +#else |
| + 1ul, |
| +#endif |
| + K(stats->nr_writeback), |
| + K(stats->nr_reclaimable), |
| + K(stats->wb_thresh), |
| + K(stats->nr_dirtied), |
| + K(stats->nr_written), |
| + K(wb->avg_write_bandwidth), |
| + stats->nr_dirty, |
| + stats->nr_io, |
| + stats->nr_more_io, |
| + stats->nr_dirty_time, |
| + wb->state); |
| +} |
| + |
| +static int cgwb_debug_stats_show(struct seq_file *m, void *v) |
| +{ |
| + struct backing_dev_info *bdi = m->private; |
| + unsigned long background_thresh; |
| + unsigned long dirty_thresh; |
| + struct bdi_writeback *wb; |
| + |
| + global_dirty_limits(&background_thresh, &dirty_thresh); |
| + |
| + rcu_read_lock(); |
| + list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) { |
| + struct wb_stats stats = { .dirty_thresh = dirty_thresh }; |
| + |
| + if (!wb_tryget(wb)) |
| + continue; |
| + |
| + collect_wb_stats(&stats, wb); |
| + |
| + /* |
| + * Calculate thresh of wb in writeback cgroup which is min of |
| + * thresh in global domain and thresh in cgroup domain. Drop |
| + * rcu lock because cgwb_calc_thresh may sleep in |
| + * cgroup_rstat_flush. We can do so here because we have a ref. |
| + */ |
| + if (mem_cgroup_wb_domain(wb)) { |
| + rcu_read_unlock(); |
| + stats.wb_thresh = min(stats.wb_thresh, cgwb_calc_thresh(wb)); |
| + rcu_read_lock(); |
| + } |
| + |
| + wb_stats_show(m, wb, &stats); |
| + |
| + wb_put(wb); |
| + } |
| + rcu_read_unlock(); |
| + |
| + return 0; |
| +} |
| +DEFINE_SHOW_ATTRIBUTE(cgwb_debug_stats); |
| + |
| static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
| { |
| bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); |
| |
| debugfs_create_file("stats", 0444, bdi->debug_dir, bdi, |
| &bdi_debug_stats_fops); |
| + debugfs_create_file("wb_stats", 0444, bdi->debug_dir, bdi, |
| + &cgwb_debug_stats_fops); |
| } |
| |
| static void bdi_debug_unregister(struct backing_dev_info *bdi) |
| { |
| debugfs_remove_recursive(bdi->debug_dir); |
| } |
| -#else |
| +#else /* CONFIG_DEBUG_FS */ |
| static inline void bdi_debug_init(void) |
| { |
| } |
| @@ -178,7 +255,7 @@ static inline void bdi_debug_register(st |
| static inline void bdi_debug_unregister(struct backing_dev_info *bdi) |
| { |
| } |
| -#endif |
| +#endif /* CONFIG_DEBUG_FS */ |
| |
| static ssize_t read_ahead_kb_store(struct device *dev, |
| struct device_attribute *attr, |
| --- a/mm/page-writeback.c~writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi |
| +++ a/mm/page-writeback.c |
| @@ -892,6 +892,25 @@ unsigned long wb_calc_thresh(struct bdi_ |
| return __wb_calc_thresh(&gdtc); |
| } |
| |
| +unsigned long cgwb_calc_thresh(struct bdi_writeback *wb) |
| +{ |
| + struct dirty_throttle_control gdtc = { GDTC_INIT_NO_WB }; |
| + struct dirty_throttle_control mdtc = { MDTC_INIT(wb, &gdtc) }; |
| + unsigned long filepages = 0, headroom = 0, writeback = 0; |
| + |
| + gdtc.avail = global_dirtyable_memory(); |
| + gdtc.dirty = global_node_page_state(NR_FILE_DIRTY) + |
| + global_node_page_state(NR_WRITEBACK); |
| + |
| + mem_cgroup_wb_stats(wb, &filepages, &headroom, |
| + &mdtc.dirty, &writeback); |
| + mdtc.dirty += writeback; |
| + mdtc_calc_avail(&mdtc, filepages, headroom); |
| + domain_dirty_limits(&mdtc); |
| + |
| + return __wb_calc_thresh(&mdtc); |
| +} |
| + |
| /* |
| * setpoint - dirty 3 |
| * f(dirty) := 1.0 + (----------------) |
| _ |
