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Wong" , 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: <20240717104524.tqlz63tsrdfixmxh@quack3> References: <20240715-mgtime-v6-0-48e5d34bd2ba@kernel.org> <20240715-mgtime-v6-3-48e5d34bd2ba@kernel.org> <20240715183211.GD103014@frogsfrogsfrogs> <7bb897f31fded59aae8d62a6796dd21feebd0642.camel@kernel.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7bb897f31fded59aae8d62a6796dd21feebd0642.camel@kernel.org> X-Rspamd-Queue-Id: BC95C21AD9 X-Spam-Flag: NO X-Spam-Score: -0.01 X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-0.01 / 50.00]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[33]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_THREE(0.00)[3]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[kernel.org,zeniv.linux.org.uk,suse.cz,goodmis.org,efficios.com,oracle.com,mit.edu,dilger.ca,fb.com,toxicpanda.com,suse.com,google.com,linux-foundation.org,lwn.net,fromorbit.com,linux.intel.com,infradead.org,gmail.com,linux.dev,arndb.de,vger.kernel.org,kvack.org]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,toxicpanda.com:email,suse.cz:dkim,suse.cz:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; RCVD_TLS_LAST(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.cz:+] X-Spam-Level: X-Spamd-Bar: / On Mon 15-07-24 15:53:42, Jeff Layton wrote: > On Mon, 2024-07-15 at 11:32 -0700, Darrick J. Wong wrote: > > 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 > > > > Sure, why not. That's simple enough to do. > > I pushed an updated mgtime branch to my git tree. Here's the updated > patch that's the only difference: > > https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git/commit/?h=mgtime&id=ee7fe6e9c0598754861c8620230f15f3de538ca5 > > Seems to build OK both with and without CONFIG_DEBUG_FS. Looks good to me. Feel free to add: Reviewed-by: Jan Kara Honza > > > >   > > >  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 > > > > > > > > -- > Jeff Layton > -- Jan Kara SUSE Labs, CR