From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 59A26134AB; Mon, 15 Jul 2024 18:32:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721068332; cv=none; b=EPRbosleZ8iUGcCnUA48JrIowgcSERA3cKtvGfgz9T20m7/cGlcxAlQIR2E+Yz1lx4DqvJOUxd8eZPs9VmRnPyWy5MklXZ2Qra6niD1bDIHxuG0xtzfkHQdi4cYGcOqhEMB70UVfCAxB8NqDCuSwW6jT1q80SD5Lsh2uSTso25U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721068332; c=relaxed/simple; bh=ptmSNcvJ6w8YaJLfeSDUkalrnWlDNwljsvsfC+1nMSo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dtfnPB1ntDq7QOcKAbyvomZ5uLXwuw5gGrmekIvcVoesUZuUj8/82abMdaAzYbgVKq0CFuWlMzC/frF0ub9woUjy06+5N8kSEXWz72a3NiUy6QNWufYxj58k/FhPicy/m/hUGpr9cTkf1UiDxbnJvUlZWoEzFyC5ysG+O8e42Zo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hAQFezqM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hAQFezqM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFBECC32782; Mon, 15 Jul 2024 18:32:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721068332; bh=ptmSNcvJ6w8YaJLfeSDUkalrnWlDNwljsvsfC+1nMSo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hAQFezqMEUEEB9I7Nxx8TIwu0q+VMSFhhWm+i036ArK6vufJmh/QUpF9e9G3BWl7U /smXWql8lshx+RMf250RPupAJezpnZFl9Rb1dPjTpxZK/Z6v9BOqW+nZnJ+Rd2GiTU OfFAzLWPkU707JHaY4a2rxxfupAAlo7SxhFI63/DwsAG4R3Z8UXG4ZQ5WUL9zu8p11 5q2uICvDIgcdda+498pCuOLLA44blyviEjZTinZ4Sg+F/i+WWvAn2Mm3ugb42O7G/d VY5BS1XfeerBLeSjQZS7uOwQZkPYIvTq0qxeXY3FO4DWhaqtwwun6pM5/aMYzl7U+h L9QpoRkhP7gXw== Date: Mon, 15 Jul 2024 11:32:11 -0700 From: "Darrick J. 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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240715-mgtime-v6-3-48e5d34bd2ba@kernel.org> 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 > >