The patch titled
Subject: writeback: support retrieving per group debug writeback stats of bdi
has been added to the -mm mm-unstable branch. Its filename is
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
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
Link: https://lkml.kernel.org/r/20240423034643.141219-3-shikemeng@xxxxxxxxxxxxxxx
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Cc: Brian Foster <bfoster@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Mateusz Guzik <mjguzik@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/writeback.h | 1
mm/backing-dev.c | 78 +++++++++++++++++++++++++++++++++++-
mm/page-writeback.c | 19 ++++++++
3 files changed, 96 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 +155,93 @@ 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",
+ cgroup_ino(wb->memcg_css->cgroup),
+ 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;
+ struct wb_stats stats;
+
+ 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 +252,7 @@ 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 + (----------------)
_
Patches currently in -mm which might be from shikemeng@xxxxxxxxxxxxxxx are
writeback-collect-stats-of-all-wb-of-bdi-in-bdi_debug_stats_show.patch
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi.patch
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix.patch
writeback-add-wb_monitorpy-script-to-monitor-writeback-info-on-bdi.patch
writeback-rename-nr_reclaimable-to-nr_dirty-in-balance_dirty_pages.patch
