From patchwork Sat Sep 14 17:07:19 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13804434 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 2732C1D589A; Sat, 14 Sep 2024 17:07:38 +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=1726333659; cv=none; b=Qt+sygecCntRf3fH1f5NjXEnG940+XDYMn1HKhEhhnit61GqN4HXzBCvKpOI3f+RffMvjW9Bi7PuC5072rUjFbzxqn5v27bUux5Rv4NiwegzZqrF6cp3jsB7nlmdIq5TMk5gDFPR44tmbadR1m1HsGSBabiDVkaCoAEvlg9gN+Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726333659; c=relaxed/simple; bh=+3a+MvaEmr8jlVEnfUS/6TeXNgPVOZEguly4I5T5qLo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=s6ni0GAUVWKHTvJIBd1nd7tizCg4gbggIjrIxZmW8lvqh9jBP9AAfp6S86RyJ6O6TbFqVeZo0qfRGb9RH1xCDIC2313bpZy7wAVCYYumfoiVuR00P6t17TfA3bvYpAmUTfCiVsYRQP4DFGsWrk+B+CYo6FKqRF/5oWCLtNDSP+g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aD+iHFXG; 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="aD+iHFXG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20F96C4CECF; Sat, 14 Sep 2024 17:07:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726333658; bh=+3a+MvaEmr8jlVEnfUS/6TeXNgPVOZEguly4I5T5qLo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=aD+iHFXGqA5JgGaTYLcJ4FNvOcGWpB4PW6RtlVSPpR24jd5+bFiFM7Pxh4qJ7JBu/ dYIJMiQoz4IGBxFkWI0inRm2+leKVKhkQPUsfiEYkIMZnGasQL+JLA9x0dgds+ULSU 6UHnPiF4cgMAYIHYTD397RggIVocHkt1rqfLCKDYAdercMlwkBqOrPnh4rMnVH2tv9 i2lBH38WJTEteBvsFxDp6mzkxg6PJ3Z5ju7h/GBfzNQsaAwis4exfZKYq5TQvOO4kz 5RJaBkotGU4z1xjOjBeeY3gXWZ4yC4qeDlfubsn5Bu1zr3Mq4cPE1xE/CqXo+y/PwG uwtpVpVM9zK1g== From: Jeff Layton Date: Sat, 14 Sep 2024 13:07:19 -0400 Subject: [PATCH v8 06/11] fs: add percpu counters for significant multigrain timestamp events Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240914-mgtime-v8-6-5bd872330bed@kernel.org> References: <20240914-mgtime-v8-0-5bd872330bed@kernel.org> In-Reply-To: <20240914-mgtime-v8-0-5bd872330bed@kernel.org> To: John Stultz , Thomas Gleixner , Stephen Boyd , Alexander Viro , Christian Brauner , Jan Kara , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Chandan Babu R , "Darrick J. Wong" , Theodore Ts'o , Andreas Dilger , Chris Mason , Josef Bacik , David Sterba , Hugh Dickins , Andrew Morton , Chuck Lever , Vadim Fedorenko Cc: Randy Dunlap , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, Jeff Layton X-Mailer: b4 0.14.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=7206; i=jlayton@kernel.org; h=from:subject:message-id; bh=+3a+MvaEmr8jlVEnfUS/6TeXNgPVOZEguly4I5T5qLo=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBm5cLGQYo9QregMNCy/xaR7pG6H/Plnuv5MCrll yGT7FFAkm2JAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZuXCxgAKCRAADmhBGVaC FY4dEACQ30o7dm6/X64AG7zaEOxgddb96T6gDj8TDTuCswZDN4BXXzgQQ3pmW+k7IGGXxgoZv1L Ah6te+pdJPDzaY3XkddSkrAAGklFh7bDRhwz8fN8W003zQIHSMLCDPT1jMdThh8U6VYDLvstq3J fY/+GyscMLHjaven87xQGU7DXJdWqWRdXfEmP4iJzBOEWti/U/YEECZ9XLSs6OMyHAGH0VV2zZM v3RDk5ivfmR4OiifBN+dR6ycULQFIjHh29mfYZQZPpNiYK2ud1uLkRmmoAznFTlt73zas407QZ2 4uiaN9PsVyHOwcraYMC5K0NeXzKPC4bm4fbnkTQ/7tLTUJ2aoNAt2tcV0aXnLNNwZQegh23JyDh HAAnq1W0uM6cjxXT21V03epzC8gmaprBda2pT2QpiNz5yMawOu+8d7M8DqN6HfBbWbCT3JMmSsi qlx05niBKzs0E1YgjmAcUG5S1RsxE+ma0nGcxRXSq9q0NziRwTw82xxPxihZ/yaF8OVPWGZ45B8 lQjwUDqgHSkbJ2XLa1YdE0CeJXhcCqpYQux5mgJw0aWJV2aa1lJOvRxWhoX2MkKyMV268AtM/gd Q8nadX2GchrFtBB7Oe906n/rM7CnD+U0z7G0xGfbbZVDWb+4AdPB5Olj+iI9A9YEG7axNm6KMBJ VObT+RUdyFXPSzA== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 New percpu counters for counting various stats around mgtimes, and a new debugfs file for displaying them when CONFIG_DEBUG_FS is enabled: - number of attempted ctime updates - number of successful i_ctime_nsec swaps - number of fine-grained timestamp fetches - number of coarse-grained floor swaps Reviewed-by: Josef Bacik Reviewed-by: Darrick J. Wong Reviewed-by: Jan Kara Signed-off-by: Jeff Layton --- fs/inode.c | 76 ++++++++++++++++++++++++++++++++++++-- include/linux/timekeeping.h | 1 + kernel/time/timekeeping.c | 3 +- kernel/time/timekeeping_debug.c | 12 ++++++ kernel/time/timekeeping_internal.h | 3 ++ 5 files changed, 90 insertions(+), 5 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index d7da9d06921f..1f0487104c71 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -21,6 +21,8 @@ #include #include #include +#include +#include #include #define CREATE_TRACE_POINTS #include @@ -101,6 +103,70 @@ long get_nr_dirty_inodes(void) return nr_dirty > 0 ? nr_dirty : 0; } +#ifdef CONFIG_DEBUG_FS +static DEFINE_PER_CPU(long, mg_ctime_updates); +static DEFINE_PER_CPU(long, mg_fine_stamps); +static DEFINE_PER_CPU(long, mg_ctime_swaps); + +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_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; +} + +#define mgtime_counter_inc(__var) this_cpu_inc(__var) + +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, "%ld %ld %ld %ld\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); + +#else /* ! CONFIG_DEBUG_FS */ + +#define mgtime_counter_inc() do { } while (0) + +#endif /* CONFIG_DEBUG_FS */ + /* * Handle nr_inode sysctl */ @@ -2655,10 +2721,9 @@ EXPORT_SYMBOL(timestamp_truncate); * * If it is multigrain, then we first see if the coarse-grained timestamp is * distinct from what we have. If so, then we'll just use that. If we have to - * get a fine-grained timestamp, then do so, and try to swap it into the floor. - * We accept the new floor value regardless of the outcome of the cmpxchg. - * After that, we try to swap the new value into i_ctime_nsec. Again, we take - * the resulting ctime, regardless of the outcome of the swap. + * get a fine-grained timestamp, then do so. After that, we try to swap the new + * value into i_ctime_nsec. We take the resulting ctime, regardless of the + * outcome of the swap. */ struct timespec64 inode_set_ctime_current(struct inode *inode) { @@ -2687,8 +2752,10 @@ struct timespec64 inode_set_ctime_current(struct inode *inode) if (timespec64_compare(&now, &ctime) <= 0) { ktime_get_real_ts64_mg(&now); now = timestamp_truncate(now, inode); + mgtime_counter_inc(mg_fine_stamps); } } + mgtime_counter_inc(mg_ctime_updates); /* No need to cmpxchg if it's exactly the same */ if (cns == now.tv_nsec && inode->i_ctime_sec == now.tv_sec) { @@ -2702,6 +2769,7 @@ struct timespec64 inode_set_ctime_current(struct inode *inode) /* If swap occurred, then we're (mostly) done */ inode->i_ctime_sec = now.tv_sec; trace_ctime_ns_xchg(inode, cns, now.tv_nsec, cur); + mgtime_counter_inc(mg_ctime_swaps); } else { /* * Was the change due to someone marking the old ctime QUERIED? diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 7aa85246c183..b9c8c597a073 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -48,6 +48,7 @@ extern void ktime_get_coarse_real_ts64(struct timespec64 *ts); /* Multigrain timestamp interfaces */ extern void ktime_get_coarse_real_ts64_mg(struct timespec64 *ts); extern void ktime_get_real_ts64_mg(struct timespec64 *ts); +extern long get_mg_floor_swaps(void); void getboottime64(struct timespec64 *ts); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 16937242b904..94b0219955a2 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -2440,7 +2440,7 @@ EXPORT_SYMBOL_GPL(ktime_get_coarse_real_ts64_mg); * regardless of the outcome of the swap. Note that this is a filesystem * specific interface and should be avoided outside of that context. */ -void ktime_get_real_ts64_mg(struct timespec64 *ts, u64 cookie) +void ktime_get_real_ts64_mg(struct timespec64 *ts) { struct timekeeper *tk = &tk_core.timekeeper; ktime_t old = atomic64_read(&mg_floor); @@ -2464,6 +2464,7 @@ void ktime_get_real_ts64_mg(struct timespec64 *ts, u64 cookie) if (atomic64_try_cmpxchg(&mg_floor, &old, mono)) { ts->tv_nsec = 0; timespec64_add_ns(ts, nsecs); + mgtime_counter_inc(mg_floor_swaps); } else { /* * Something has changed mg_floor since "old" was diff --git a/kernel/time/timekeeping_debug.c b/kernel/time/timekeeping_debug.c index b73e8850e58d..9a3792072762 100644 --- a/kernel/time/timekeeping_debug.c +++ b/kernel/time/timekeeping_debug.c @@ -17,6 +17,9 @@ #define NUM_BINS 32 +/* incremented every time mg_floor is updated */ +DEFINE_PER_CPU(long, mg_floor_swaps); + static unsigned int sleep_time_bin[NUM_BINS] = {0}; static int tk_debug_sleep_time_show(struct seq_file *s, void *data) @@ -53,3 +56,12 @@ void tk_debug_account_sleep_time(const struct timespec64 *t) (s64)t->tv_sec, t->tv_nsec / NSEC_PER_MSEC); } +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; +} diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h index 4ca2787d1642..2b49332b45a5 100644 --- a/kernel/time/timekeeping_internal.h +++ b/kernel/time/timekeeping_internal.h @@ -11,8 +11,11 @@ */ #ifdef CONFIG_DEBUG_FS extern void tk_debug_account_sleep_time(const struct timespec64 *t); +DECLARE_PER_CPU(long, mg_floor_swaps); +#define mgtime_counter_inc(__var) this_cpu_inc(__var) #else #define tk_debug_account_sleep_time(x) +#define mgtime_counter_inc() do { } while (0) #endif #ifdef CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE