Keep a pair of percpu counters so we can track what proportion of timestamps is fine-grained.
Signed-off-by: Jeff Layton <[email protected]> --- fs/inode.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/fs/inode.c b/fs/inode.c index 12790a26102c..5b5a1a8c0bb7 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -21,6 +21,8 @@ #include <linux/list_lru.h> #include <linux/iversion.h> #include <linux/rw_hint.h> +#include <linux/seq_file.h> +#include <linux/debugfs.h> #include <trace/events/writeback.h> #define CREATE_TRACE_POINTS #include <trace/events/timestamp.h> @@ -64,6 +66,10 @@ static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock); /* Don't send out a ctime lower than this (modulo backward clock jumps). */ static __cacheline_aligned_in_smp ktime_t ctime_floor; + +static struct percpu_counter mg_fine_ts; +static struct percpu_counter mg_coarse_ts; + /* * Empty aops. Can be used for the cases where the user does not * define any of the address_space operations. @@ -2636,6 +2642,9 @@ struct timespec64 inode_set_ctime_current(struct inode *inode) trace_ctime_floor_update(inode, floor, now, old); if (old != floor) now = old; + percpu_counter_inc(&mg_fine_ts); + } else { + percpu_counter_inc(&mg_coarse_ts); } retry: /* Try to swap the ctime into place. */ @@ -2711,3 +2720,32 @@ umode_t mode_strip_sgid(struct mnt_idmap *idmap, return mode & ~S_ISGID; } EXPORT_SYMBOL(mode_strip_sgid); + +static int mgts_show(struct seq_file *s, void *p) +{ + u64 fine = percpu_counter_sum(&mg_fine_ts); + u64 coarse = percpu_counter_sum(&mg_coarse_ts); + + seq_printf(s, "%llu %llu\n", fine, coarse); + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(mgts); + +static int __init mg_debugfs_init(void) +{ + int ret = percpu_counter_init(&mg_fine_ts, 0, GFP_KERNEL); + + if (ret) + return ret; + + ret = percpu_counter_init(&mg_coarse_ts, 0, GFP_KERNEL); + if (ret) { + percpu_counter_destroy(&mg_fine_ts); + return ret; + } + + debugfs_create_file("multigrain_timestamps", S_IFREG | S_IRUGO, NULL, NULL, &mgts_fops); + return 0; +} +late_initcall(mg_debugfs_init); -- 2.45.2