From: Uladzislau Rezki <urezki@gmail.com>
To: "Paul E. McKenney" <paulmck@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Uladzislau Rezki <urezki@gmail.com>,
rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, rostedt@goodmis.org
Subject: Re: [PATCH rcu 13/14] workqueue: Make queue_rcu_work() use call_rcu_flush()
Date: Mon, 24 Oct 2022 18:25:30 +0200 [thread overview]
Message-ID: <Y1a8ei1h7SzyYZx9@pc636> (raw)
In-Reply-To: <20221024153958.GY5600@paulmck-ThinkPad-P17-Gen-1>
>
> You guys might need to agree on the definition of "good" here. Or maybe
> understand the differences in your respective platforms' definitions of
> "good". ;-)
>
Indeed. Bad is when once per-millisecond infinitely :) At least in such use
workload a can detect a power delta and power gain. Anyway, below is a new
trace where i do not use "flush" variant for the kvfree_rcu():
<snip>
1. Home screen swipe:
rcuop/0-15 [003] d..1 1792.767750: rcu_batch_start: rcu_preempt CBs=1003 bl=10
rcuop/2-33 [002] d..1 1792.771717: rcu_batch_start: rcu_preempt CBs=934 bl=10
rcuop/3-40 [001] d..1 1794.811816: rcu_batch_start: rcu_preempt CBs=1508 bl=11
rcuop/1-26 [003] d..1 1797.116382: rcu_batch_start: rcu_preempt CBs=2127 bl=16
rcuop/4-48 [001] d..1 1797.124422: rcu_batch_start: rcu_preempt CBs=95 bl=10
rcuop/5-55 [002] d..1 1797.124731: rcu_batch_start: rcu_preempt CBs=143 bl=10
rcuop/6-62 [005] d..1 1798.911719: rcu_batch_start: rcu_preempt CBs=132 bl=10
rcuop/2-33 [002] d..1 1803.003966: rcu_batch_start: rcu_preempt CBs=3797 bl=29
rcuop/0-15 [003] d..1 1803.004707: rcu_batch_start: rcu_preempt CBs=2969 bl=23
2. App launches:
rcuop/4-48 [005] d..1 1831.087612: rcu_batch_start: rcu_preempt CBs=6141 bl=47
rcuop/7-69 [007] d..1 1831.095578: rcu_batch_start: rcu_preempt CBs=5464 bl=42
rcuop/5-55 [004] d..1 1832.703571: rcu_batch_start: rcu_preempt CBs=8461 bl=66
rcuop/0-15 [004] d..1 1833.731603: rcu_batch_start: rcu_preempt CBs=2548 bl=19
rcuop/1-26 [006] d..1 1833.743691: rcu_batch_start: rcu_preempt CBs=2567 bl=20
rcuop/2-33 [006] d..1 1833.744005: rcu_batch_start: rcu_preempt CBs=2359 bl=18
rcuop/3-40 [006] d..1 1833.744286: rcu_batch_start: rcu_preempt CBs=3681 bl=28
rcuop/4-48 [002] d..1 1838.079777: rcu_batch_start: rcu_preempt CBs=10444 bl=81
rcuop/7-69 [001] d..1 1838.080375: rcu_batch_start: rcu_preempt CBs=12572 bl=98
<...>-62 [002] d..1 1838.080646: rcu_batch_start: rcu_preempt CBs=14135 bl=110
rcuop/6-62 [000] d..1 1838.087722: rcu_batch_start: rcu_preempt CBs=10839 bl=84
<...>-62 [003] d..1 1839.227022: rcu_batch_start: rcu_preempt CBs=1834 bl=14
<...>-26 [001] d..1 1839.963315: rcu_batch_start: rcu_preempt CBs=5769 bl=45
rcuop/2-33 [001] d..1 1839.966485: rcu_batch_start: rcu_preempt CBs=3789 bl=29
<...>-40 [001] d..1 1839.966596: rcu_batch_start: rcu_preempt CBs=6425 bl=50
rcuop/2-33 [005] d..1 1840.541272: rcu_batch_start: rcu_preempt CBs=825 bl=10
rcuop/2-33 [005] d..1 1840.547724: rcu_batch_start: rcu_preempt CBs=44 bl=10
rcuop/2-33 [005] d..1 1841.075759: rcu_batch_start: rcu_preempt CBs=516 bl=10
rcuop/0-15 [002] d..1 1841.695716: rcu_batch_start: rcu_preempt CBs=6312 bl=49
rcuop/0-15 [003] d..1 1841.709714: rcu_batch_start: rcu_preempt CBs=39 bl=10
rcuop/5-55 [004] d..1 1843.112442: rcu_batch_start: rcu_preempt CBs=16007 bl=125
rcuop/5-55 [004] d..1 1843.115444: rcu_batch_start: rcu_preempt CBs=7901 bl=61
rcuop/6-62 [001] dn.1 1843.123983: rcu_batch_start: rcu_preempt CBs=8427 bl=65
rcuop/6-62 [006] d..1 1843.412383: rcu_batch_start: rcu_preempt CBs=981 bl=10
rcuop/0-15 [003] d..1 1844.659812: rcu_batch_start: rcu_preempt CBs=1851 bl=14
rcuop/0-15 [003] d..1 1844.667790: rcu_batch_start: rcu_preempt CBs=135 bl=10
<snip>
it is much more better. But. As i wrote earlier there is a patch that i have submitted
some time ago improving kvfree_rcu() batching:
<snip>
commit 51824b780b719c53113dc39e027fbf670dc66028
Author: Uladzislau Rezki (Sony) <urezki@gmail.com>
Date: Thu Jun 30 18:33:35 2022 +0200
rcu/kvfree: Update KFREE_DRAIN_JIFFIES interval
Currently the monitor work is scheduled with a fixed interval of HZ/20,
which is roughly 50 milliseconds. The drawback of this approach is
low utilization of the 512 page slots in scenarios with infrequence
kvfree_rcu() calls. For example on an Android system:
<snip>
The trace that i posted was taken without it.
--
Uladzislau Rezki
next prev parent reply other threads:[~2022-10-24 17:50 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-19 22:51 [PATCH rcu 0/14] Lazy call_rcu() updates for v6.2 Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 01/14] rcu: Simplify rcu_init_nohz() cpumask handling Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 02/14] rcu: Fix late wakeup when flush of bypass cblist happens Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 03/14] rcu: Fix missing nocb gp wake on rcu_barrier() Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 04/14] rcu: Make call_rcu() lazy to save power Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 05/14] rcu: Refactor code a bit in rcu_nocb_do_flush_bypass() Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 06/14] rcu: Shrinker for lazy rcu Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 07/14] rcuscale: Add laziness and kfree tests Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 08/14] percpu-refcount: Use call_rcu_flush() for atomic switch Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 09/14] rcu/sync: Use call_rcu_flush() instead of call_rcu Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 10/14] rcu/rcuscale: Use call_rcu_flush() for async reader test Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 11/14] rcu/rcutorture: Use call_rcu_flush() where needed Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 12/14] scsi/scsi_error: Use call_rcu_flush() instead of call_rcu() Paul E. McKenney
2022-10-19 22:51 ` [PATCH rcu 13/14] workqueue: Make queue_rcu_work() use call_rcu_flush() Paul E. McKenney
2022-10-24 0:36 ` Joel Fernandes
2022-10-24 3:15 ` Paul E. McKenney
2022-10-24 10:49 ` Uladzislau Rezki
2022-10-24 12:23 ` Uladzislau Rezki
2022-10-24 14:31 ` Joel Fernandes
2022-10-24 15:39 ` Paul E. McKenney
2022-10-24 16:25 ` Uladzislau Rezki [this message]
2022-10-24 16:48 ` Paul E. McKenney
2022-10-24 16:55 ` Uladzislau Rezki
2022-10-24 17:08 ` Uladzislau Rezki
2022-10-24 17:20 ` Joel Fernandes
2022-10-24 17:35 ` Paul E. McKenney
2022-10-24 20:12 ` Joel Fernandes
2022-10-24 20:16 ` Joel Fernandes
2022-10-25 10:48 ` Uladzislau Rezki
2022-10-25 15:05 ` Joel Fernandes
2022-10-26 20:35 ` Uladzislau Rezki
2022-10-24 20:19 ` Paul E. McKenney
2022-10-24 20:26 ` Joel Fernandes
2022-10-24 17:40 ` Uladzislau Rezki
2022-10-24 20:08 ` Joel Fernandes
2022-10-25 10:47 ` Uladzislau Rezki
2022-10-28 21:23 ` Joel Fernandes
2022-10-28 21:42 ` Joel Fernandes
2022-10-31 13:21 ` Uladzislau Rezki
2022-10-31 13:37 ` Joel Fernandes
2022-10-31 18:15 ` Joel Fernandes
2022-11-01 4:49 ` Uladzislau Rezki
2022-10-24 16:54 ` Joel Fernandes
2022-10-19 22:51 ` [PATCH rcu 14/14] rxrpc: Use call_rcu_flush() instead of call_rcu() Paul E. McKenney
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