From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
bobby.prani@gmail.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH v3 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter
Date: Tue, 24 Jan 2017 13:51:28 -0800 [thread overview]
Message-ID: <1485294689-11485-17-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170124215111.GB2269@linux.vnet.ibm.com>
Expedited grace periods no longer fall back to normal grace periods
in response to lock contention, given that expedited grace periods
now use the rcu_node tree so as to avoid contention. This commit
therfore removes the expedited_normal counter.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
---
Documentation/RCU/trace.txt | 5 +----
kernel/rcu/tree.h | 1 -
kernel/rcu/tree_trace.c | 3 +--
3 files changed, 2 insertions(+), 7 deletions(-)
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index 00a3a38b375a..6549012033f9 100644
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -237,7 +237,7 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of
The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:
-s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
+s=21872 wd1=0 wd2=0 wd3=5 enq=0 sc=21872
These fields are as follows:
@@ -249,9 +249,6 @@ o "wd1", "wd2", and "wd3" are the number of times that an attempt
completed an expedited grace period that satisfies the attempted
request. "Our work is done."
-o "n" is number of times that a concurrent CPU-hotplug operation
- forced a fallback to a normal grace period.
-
o "enq" is the number of quiescent states still outstanding.
o "sc" is the number of times that the attempt to start a
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index fe98dd24adf8..8f750dffb0dd 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -521,7 +521,6 @@ struct rcu_state {
struct mutex exp_mutex; /* Serialize expedited GP. */
struct mutex exp_wake_mutex; /* Serialize wakeup. */
unsigned long expedited_sequence; /* Take a ticket. */
- atomic_long_t expedited_normal; /* # fallbacks to normal. */
atomic_t expedited_need_qs; /* # CPUs left to check in. */
struct swait_queue_head expedited_wq; /* Wait for check-ins. */
int ncpus_snap; /* # CPUs seen last time. */
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index b1f28972872c..2e932cd1da31 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -194,9 +194,8 @@ static int show_rcuexp(struct seq_file *m, void *v)
s2 += atomic_long_read(&rdp->exp_workdone2);
s3 += atomic_long_read(&rdp->exp_workdone3);
}
- seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
+ seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu enq=%d sc=%lu\n",
rsp->expedited_sequence, s0, s1, s2, s3,
- atomic_long_read(&rsp->expedited_normal),
atomic_read(&rsp->expedited_need_qs),
rsp->expedited_sequence / 2);
return 0;
--
2.5.2
next prev parent reply other threads:[~2017-01-24 21:51 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-14 9:12 [PATCH tip/core/rcu 0/20] Miscellaneous fixes for 4.11 Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 01/20] rcu: update: Make RCU_EXPEDITE_BOOT be the default Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 02/20] lockdep: Make RCU suspicious-access splats use pr_err Paul E. McKenney
2017-01-16 7:53 ` Josh Triplett
2017-01-17 1:06 ` Paul E. McKenney
2017-01-16 17:21 ` Peter Zijlstra
2017-01-16 20:59 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 03/20] Fix: Disable sys_membarrier when nohz_full is enabled Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 04/20] rcu: Only dump stalled-tasks stacks if there was a real stall Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 05/20] rcu: Remove unneeded rcu_process_callbacks() declarations Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 06/20] rcu: Remove unused but set variable Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 07/20] rcu: Remove short-term CPU kicking Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 08/20] rcu: Add long-term " Paul E. McKenney
2017-01-16 7:58 ` Josh Triplett
2017-01-17 1:07 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 09/20] rcu: Once again use NMI-based stack traces in stall warnings Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 10/20] rcu: Add functions to test for trivial grace periods Paul E. McKenney
2017-01-16 8:01 ` Josh Triplett
2017-01-17 0:32 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 11/20] sched,rcu: Make cond_resched() provide RCU quiescent state Paul E. McKenney
2017-01-16 8:08 ` Josh Triplett
2017-01-16 11:38 ` Paul E. McKenney
2017-01-16 17:11 ` Peter Zijlstra
2017-01-17 0:54 ` Paul E. McKenney
2017-01-17 10:51 ` Michal Hocko
2017-01-17 12:05 ` Paul E. McKenney
2017-01-17 12:11 ` Michal Hocko
2017-01-18 2:10 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 12/20] rcu: Re-enable TASKS_RCU for User Mode Linux Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 13/20] rcu: Don't wake rcuc/X kthreads on NOCB CPUs Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 14/20] rcu: Add comment headers to expedited-grace-period counter functions Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 15/20] rcu: Make rcu_cpu_starting() use its "cpu" argument Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 16/20] rcu: Enable RCU tracepoints by default to aid in debugging Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 17/20] rcu: Fix comment in rcu_organize_nocb_kthreads() Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 18/20] llist: Clarify comments about when locking is needed Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 19/20] rcu: Eliminate unused expedited_normal counter Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 20/20] rcu: Add lockdep checks to synchronous expedited primitives Paul E. McKenney
2017-01-16 8:09 ` [PATCH tip/core/rcu 0/20] Miscellaneous fixes for 4.11 Josh Triplett
2017-01-17 1:07 ` Paul E. McKenney
2017-01-18 2:53 ` Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 01/18] rcu: update: Make RCU_EXPEDITE_BOOT be the default Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err Paul E. McKenney
2017-01-21 20:40 ` Josh Triplett
2017-01-23 19:30 ` Paul E. McKenney
2017-01-23 22:33 ` Josh Triplett
2017-01-24 0:13 ` Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 03/18] Fix: Disable sys_membarrier when nohz_full is enabled Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 04/18] rcu: Only dump stalled-tasks stacks if there was a real stall Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 05/18] rcu: Remove unneeded rcu_process_callbacks() declarations Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 06/18] rcu: Remove unused but set variable Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Paul E. McKenney
2017-01-21 20:41 ` Josh Triplett
2017-01-21 20:42 ` Josh Triplett
2017-01-23 19:34 ` Paul E. McKenney
2017-01-23 20:25 ` Josh Triplett
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 08/18] rcu: Remove short-term " Paul E. McKenney
2017-01-21 20:43 ` Josh Triplett
2017-01-23 19:36 ` Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 09/18] rcu: Once again use NMI-based stack traces in stall warnings Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 10/18] rcu: Re-enable TASKS_RCU for User Mode Linux Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 11/18] rcu: Don't wake rcuc/X kthreads on NOCB CPUs Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 12/18] rcu: Add comment headers to expedited-grace-period counter functions Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 13/18] rcu: Make rcu_cpu_starting() use its "cpu" argument Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 14/18] rcu: Enable RCU tracepoints by default to aid in debugging Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 15/18] rcu: Fix comment in rcu_organize_nocb_kthreads() Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 16/18] llist: Clarify comments about when locking is needed Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 18/18] rcu: Add lockdep checks to synchronous expedited primitives Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 0/18] Miscellaneous fixes for 4.11 Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 01/18] rcu: update: Make RCU_EXPEDITE_BOOT be the default Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 03/18] Fix: Disable sys_membarrier when nohz_full is enabled Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 04/18] rcu: Only dump stalled-tasks stacks if there was a real stall Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 05/18] rcu: Remove unneeded rcu_process_callbacks() declarations Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 06/18] rcu: Remove unused but set variable Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 08/18] rcu: Remove short-term " Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 09/18] rcu: Once again use NMI-based stack traces in stall warnings Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 10/18] rcu: Re-enable TASKS_RCU for User Mode Linux Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 11/18] rcu: Don't wake rcuc/X kthreads on NOCB CPUs Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 12/18] rcu: Add comment headers to expedited-grace-period counter functions Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 13/18] rcu: Make rcu_cpu_starting() use its "cpu" argument Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 14/18] rcu: Enable RCU tracepoints by default to aid in debugging Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 15/18] rcu: Fix comment in rcu_organize_nocb_kthreads() Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 16/18] llist: Clarify comments about when locking is needed Paul E. McKenney
2017-01-24 21:51 ` Paul E. McKenney [this message]
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 18/18] rcu: Add lockdep checks to synchronous expedited primitives Paul E. McKenney
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