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Wong" To: Jeff Layton Cc: Alexander Viro , Christian Brauner , Jan Kara , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Chandan Babu R , Theodore Ts'o , Andreas Dilger , Chris Mason , Josef Bacik , David Sterba , Hugh Dickins , Andrew Morton , Jonathan Corbet , Dave Chinner , Andi Kleen , Christoph Hellwig , Uros Bizjak , Kent Overstreet , Arnd Bergmann , Randy Dunlap , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v6 3/9] fs: add percpu counters for significant multigrain timestamp events Message-ID: <20240715183211.GD103014@frogsfrogsfrogs> References: <20240715-mgtime-v6-0-48e5d34bd2ba@kernel.org> <20240715-mgtime-v6-3-48e5d34bd2ba@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240715-mgtime-v6-3-48e5d34bd2ba@kernel.org> X-Stat-Signature: nmd3az4sknkhe7s7afc1un9h1qt1carg X-Rspamd-Queue-Id: 530DC18000F X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1721068333-112667 X-HE-Meta: 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 lhKJua8V p05ztBlZ/4xYhf7SaAtTTXLOmyCEMohoQn2oU/4OCK2ciMGDJnMvE+Po2rEAqGo9vQmc1YAn5ITI6oGobooYdBmZP2FGYdvI+lVBmrGUPlZWaISQX7QzPOgXagjROU//i7D5DuEF7CGne7CsdvKgS4m/4YopMsskIT8FNrJUlUubD73lGSwYAXImxdTkUf3zfs9rmFsPSnAsSVHD+fraBgKn6GY57+KO4NtZXdvtdH9H+VPtIZhTdOsNQbGMZfJ5zTp+QteJpz3H+fO9220qBvTiL/vFeNZKviIeUWtM+cwZTNesjMPIPIcIzxiw67ETiBJsJ32aB5yicOiOnsRVJcPMUUw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 15, 2024 at 08:48:54AM -0400, Jeff Layton wrote: > Four percpu counters for counting various stats around mgtimes, and a > new debugfs file for displaying them: > > - number of attempted ctime updates > - number of successful i_ctime_nsec swaps > - number of fine-grained timestamp fetches > - number of floor value swaps > > Reviewed-by: Josef Bacik > Signed-off-by: Jeff Layton > --- > fs/inode.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 69 insertions(+), 1 deletion(-) > > diff --git a/fs/inode.c b/fs/inode.c > index 869994285e87..fff844345c35 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -21,6 +21,8 @@ > #include > #include > #include > +#include > +#include > #include > #define CREATE_TRACE_POINTS > #include > @@ -80,6 +82,10 @@ EXPORT_SYMBOL(empty_aops); > > static DEFINE_PER_CPU(unsigned long, nr_inodes); > static DEFINE_PER_CPU(unsigned long, nr_unused); > +static DEFINE_PER_CPU(unsigned long, mg_ctime_updates); > +static DEFINE_PER_CPU(unsigned long, mg_fine_stamps); > +static DEFINE_PER_CPU(unsigned long, mg_floor_swaps); > +static DEFINE_PER_CPU(unsigned long, mg_ctime_swaps); Should this all get switched off if CONFIG_DEBUG_FS=n? --D > > static struct kmem_cache *inode_cachep __ro_after_init; > > @@ -101,6 +107,42 @@ static inline long get_nr_inodes_unused(void) > return sum < 0 ? 0 : sum; > } > > +static long get_mg_ctime_updates(void) > +{ > + int i; > + long sum = 0; > + for_each_possible_cpu(i) > + sum += per_cpu(mg_ctime_updates, i); > + return sum < 0 ? 0 : sum; > +} > + > +static long get_mg_fine_stamps(void) > +{ > + int i; > + long sum = 0; > + for_each_possible_cpu(i) > + sum += per_cpu(mg_fine_stamps, i); > + return sum < 0 ? 0 : sum; > +} > + > +static long get_mg_floor_swaps(void) > +{ > + int i; > + long sum = 0; > + for_each_possible_cpu(i) > + sum += per_cpu(mg_floor_swaps, i); > + return sum < 0 ? 0 : sum; > +} > + > +static long get_mg_ctime_swaps(void) > +{ > + int i; > + long sum = 0; > + for_each_possible_cpu(i) > + sum += per_cpu(mg_ctime_swaps, i); > + return sum < 0 ? 0 : sum; > +} > + > long get_nr_dirty_inodes(void) > { > /* not actually dirty inodes, but a wild approximation */ > @@ -2655,6 +2697,7 @@ struct timespec64 inode_set_ctime_current(struct inode *inode) > > /* Get a fine-grained time */ > fine = ktime_get(); > + this_cpu_inc(mg_fine_stamps); > > /* > * If the cmpxchg works, we take the new floor value. If > @@ -2663,11 +2706,14 @@ struct timespec64 inode_set_ctime_current(struct inode *inode) > * as good, so keep it. > */ > old = floor; > - if (!atomic64_try_cmpxchg(&ctime_floor, &old, fine)) > + if (atomic64_try_cmpxchg(&ctime_floor, &old, fine)) > + this_cpu_inc(mg_floor_swaps); > + else > fine = old; > now = ktime_mono_to_real(fine); > } > } > + this_cpu_inc(mg_ctime_updates); > now_ts = timestamp_truncate(ktime_to_timespec64(now), inode); > cur = cns; > > @@ -2682,6 +2728,7 @@ struct timespec64 inode_set_ctime_current(struct inode *inode) > /* If swap occurred, then we're (mostly) done */ > inode->i_ctime_sec = now_ts.tv_sec; > trace_ctime_ns_xchg(inode, cns, now_ts.tv_nsec, cur); > + this_cpu_inc(mg_ctime_swaps); > } else { > /* > * Was the change due to someone marking the old ctime QUERIED? > @@ -2751,3 +2798,24 @@ 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) > +{ > + long ctime_updates = get_mg_ctime_updates(); > + long ctime_swaps = get_mg_ctime_swaps(); > + long fine_stamps = get_mg_fine_stamps(); > + long floor_swaps = get_mg_floor_swaps(); > + > + seq_printf(s, "%lu %lu %lu %lu\n", > + ctime_updates, ctime_swaps, fine_stamps, floor_swaps); > + return 0; > +} > + > +DEFINE_SHOW_ATTRIBUTE(mgts); > + > +static int __init mg_debugfs_init(void) > +{ > + debugfs_create_file("multigrain_timestamps", S_IFREG | S_IRUGO, NULL, NULL, &mgts_fops); > + return 0; > +} > +late_initcall(mg_debugfs_init); > > -- > 2.45.2 > >