From nobody Thu Nov 28 11:04:29 2024 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 455A621949F; Wed, 2 Oct 2024 21:27:36 +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=1727904457; cv=none; b=gp79FopKyihvvWMGDgBzSsB3sxzCnHG5ffkLCcRq6SyldOjyNBdEt1x+QGdh6WruWGnF6zytcLTDVgxZO+XfOhKZ7zw1aximmKLpU0PGkLsnQr7OxeIj5lZcsqGp/MczEJLl5qVEPjiMYAcSIkLq0gKmRuXUYROZTKnArzEltoQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727904457; c=relaxed/simple; bh=b4XkKth37w2ravUWOahimfnL3UOfVbEBD3lD+3rp+1s=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sM8cNeimZ6CgS18RXKmY6Jy0PbJpKTF+bO/Psl05blLIX2xH5oCAW0jqHxoTXMN909tmpguKX/aVIM01nrYFjntoRYPr56sJRQUeLUOYjHBJfYdVmG7kra7jj2dwBlJizsFff6d7pIo8h5N31zyMtHLK1pz+vwWtSNrrBZW42js= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G3mMkbdg; 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="G3mMkbdg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55601C4CED1; Wed, 2 Oct 2024 21:27:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727904456; bh=b4XkKth37w2ravUWOahimfnL3UOfVbEBD3lD+3rp+1s=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=G3mMkbdg0nkDEyn6L/6plWzGy8rzM311X3HHbMz6R3Ai1VYHlupggE7MRYdxecBcW Xvk6ll6KZR/g9zl7uCaka+nNH7x9Tm/RIkT5vO6uSHNqrUjFrtM95g8heH5M+lCE55 F8sgy2iJ9fYi2MZGAAxh7tC2DGiC+V5GkjwU7zP25bmpQ/aYrgzhRDQUPnIsshqeKy O7Jkn3FCOz/3z+OTJtQd0O6UxWljUiDGrmddv3D/etWQiDuDYhcmmN0fD6Ll8pFgyi DBGz2Fo7ZjiuVE0X7WaIHym/aM5Pjo+l4xsKTeBPi+9qboJDAz98MsoDdHe55s5REo dVuTX5zzfKQ1A== From: Jeff Layton Date: Wed, 02 Oct 2024 17:27:17 -0400 Subject: [PATCH v10 02/12] timekeeping: add percpu counter for tracking floor swap events Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20241002-mgtime-v10-2-d1c4717f5284@kernel.org> References: <20241002-mgtime-v10-0-d1c4717f5284@kernel.org> In-Reply-To: <20241002-mgtime-v10-0-d1c4717f5284@kernel.org> To: John Stultz , Thomas Gleixner , Stephen Boyd , Alexander Viro , Christian Brauner , Jan Kara , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Randy Dunlap , 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: 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 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3634; i=jlayton@kernel.org; h=from:subject:message-id; bh=b4XkKth37w2ravUWOahimfnL3UOfVbEBD3lD+3rp+1s=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBm/bq/KG7g3gRmiuGWZ6tpbobqHKVwsPLvCl1+2 PakkzoH/7uJAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZv26vwAKCRAADmhBGVaC FZRZD/4yysdw6oqodqdrDqoDwQHs/Q4CF/xQT2tRHqA4QItHNsZTxwidAffBRsnGrGPeTIgeMCM eYGyGB9p4u3XxLEb8dhRFOW1RBgcQ/Cjr8cpZH6SZLYpRAk6GIcclb7JSx0Z+ZsLsb3raxWip/q aQkME57KDFHa5SU4k6wWAI43OaKhloW9psmHOc+VuX08saDovMS29GzzdVVAjB04fD6FVnJ0bOw LhNaYNNOKXmuoYPbwXaeS79CaJBEsoC4hSLmofWpFHtXZSM0eMXenbt01hkg0YPIERLodPld9rp iR7KGQ74j0CMmpjZaG/iu8mh33FVzNhkaSdq0w4OuN8UNcCDibrHS5/mOt4wdm3uhMR74E6vON+ 0hkVua/1WjZWCbWA9MiE7S8g3sORCoVEP2BIlNBS3fMnIDVCW9YjyntS4bsTRJnYK5cVmuROgko 7sLr656frMTXl0fy01yglfhU+MXQcqqrmxOiXyRELla8YEX+AKon8oWhvegEV/KJV2LWq3sc2PJ TaaxJQMW9FMLYqn5/ddC7uMEmiMU4fHMlL7JHWzMIzBCVTUE4F3nzpMWHemwN+a44HbOhkzhyQc 0gsIzOEweoF4Kk/yBwXoIpBJneQyP9cglaRlMWlyaD4SLndBdD4EgyTrBtFMAYZncjdhhZwr8Uz ptEgKiXkkzgo4IQ== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 The mgtime_floor value is a global variable for tracking the latest fine-grained timestamp handed out. Because it's a global, track the number of times that a new floor value is assigned. Add a new percpu counter to the timekeeping code to track the number of floor swap events that have occurred. A later patch will add a debugfs file to display this counter alongside other stats involving multigrain timestamps. Tested-by: Randy Dunlap # documentation bits Signed-off-by: Jeff Layton --- include/linux/timekeeping.h | 1 + kernel/time/timekeeping.c | 1 + kernel/time/timekeeping_debug.c | 14 ++++++++++++++ kernel/time/timekeeping_internal.h | 15 +++++++++++++++ 4 files changed, 31 insertions(+) diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 7aa85246c183576b039c02af4abba02b4a09ef9d..84a035e86ac811f9e7b1649246b= 71c9296519149 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 unsigned long timekeeping_get_mg_floor_swaps(void); =20 void getboottime64(struct timespec64 *ts); =20 diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index ebfe846ebde35850c3e4d9c2cc45642c983d137f..e8b713e8ce5553f9e7de96c8e7c= 089714e0aa7a4 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -2488,6 +2488,7 @@ void ktime_get_real_ts64_mg(struct timespec64 *ts) if (atomic64_try_cmpxchg(&mg_floor, &old, mono)) { ts->tv_nsec =3D 0; timespec64_add_ns(ts, nsecs); + timekeeping_inc_mg_floor_swaps(); } else { /* * Another task changed mg_floor since "old" was fetched. diff --git a/kernel/time/timekeeping_debug.c b/kernel/time/timekeeping_debu= g.c index b73e8850e58d9c5b291559f475e67c7ed47c2db3..36d359cad7ca1d821bf42f59b3e= 50f89b14afd40 100644 --- a/kernel/time/timekeeping_debug.c +++ b/kernel/time/timekeeping_debug.c @@ -17,6 +17,9 @@ =20 #define NUM_BINS 32 =20 +/* incremented every time mg_floor is updated */ +DEFINE_PER_CPU(unsigned long, timekeeping_mg_floor_swaps); + static unsigned int sleep_time_bin[NUM_BINS] =3D {0}; =20 static int tk_debug_sleep_time_show(struct seq_file *s, void *data) @@ -53,3 +56,14 @@ void tk_debug_account_sleep_time(const struct timespec64= *t) (s64)t->tv_sec, t->tv_nsec / NSEC_PER_MSEC); } =20 +unsigned long timekeeping_get_mg_floor_swaps(void) +{ + unsigned long sum =3D 0; + int cpu; + + for_each_possible_cpu(cpu) + sum +=3D data_race(per_cpu(timekeeping_mg_floor_swaps, cpu)); + + return sum; +} + diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_i= nternal.h index 4ca2787d1642e2f52bf985607ca3b03785cf9a50..0bbae825bc0226e4eed64e73fe3= b454986c7573f 100644 --- a/kernel/time/timekeeping_internal.h +++ b/kernel/time/timekeeping_internal.h @@ -10,9 +10,24 @@ * timekeeping debug functions */ #ifdef CONFIG_DEBUG_FS + +DECLARE_PER_CPU(unsigned long, timekeeping_mg_floor_swaps); + +static inline void timekeeping_inc_mg_floor_swaps(void) +{ + this_cpu_inc(timekeeping_mg_floor_swaps); +} + extern void tk_debug_account_sleep_time(const struct timespec64 *t); + #else + #define tk_debug_account_sleep_time(x) + +static inline void timekeeping_inc_mg_floor_swaps(void) +{ +} + #endif =20 #ifdef CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE --=20 2.46.2