From: Nicholas Piggin <npiggin@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
"linux-kernel @ vger . kernel . org"
<linux-kernel@vger.kernel.org>
Subject: [PATCH v2 10/12] locking/qspinlock: paravirt use simple trylock in case idx overflows
Date: Wed, 13 Jul 2022 17:07:02 +1000 [thread overview]
Message-ID: <20220713070704.308394-11-npiggin@gmail.com> (raw)
In-Reply-To: <20220713070704.308394-1-npiggin@gmail.com>
The mcs node overflow fallback locking case does not have to use
pv_hybrid_queued_unfair_trylock as the trylock, which reduces the
differences between pv and !pv cases.
This was likely an artifact of function renaming making it use the pv
trylock, which is not a bug but it is unexpected.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
kernel/locking/qspinlock.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index df6d8af8f2a9..2ebb946a6b80 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -800,13 +800,8 @@ static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, b
*/
if (unlikely(idx >= MAX_NODES)) {
lockevent_inc(lock_no_node);
- if (paravirt) {
- while (!pv_hybrid_queued_unfair_trylock(lock))
- cpu_relax();
- } else {
- while (!queued_spin_trylock(lock))
- cpu_relax();
- }
+ while (!queued_spin_trylock(lock))
+ cpu_relax();
goto release;
}
--
2.35.1
next prev parent reply other threads:[~2022-07-13 7:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-13 7:06 [PATCH v2 00/12] locking/qspinlock: simplify code generation Nicholas Piggin
2022-07-13 7:06 ` [PATCH v2 01/12] locking/qspinlock: remove pv_node abstraction Nicholas Piggin
2022-07-13 7:06 ` [PATCH v2 02/12] locking/qspinlock: inline mcs_spinlock functions into qspinlock Nicholas Piggin
2022-07-13 7:06 ` [PATCH v2 03/12] locking/qspinlock: split common mcs queueing code into its own function Nicholas Piggin
2022-07-13 7:06 ` [PATCH v2 04/12] locking/qspinlock: move pv lock word helpers into qspinlock.c Nicholas Piggin
2022-07-13 7:06 ` [PATCH v2 05/12] locking/qspinlock: be less clever with the preprocessor Nicholas Piggin
2022-07-13 7:06 ` [PATCH v2 06/12] locking/qspinlock: merge qspinlock_paravirt.h into qspinlock.c Nicholas Piggin
2022-07-14 14:16 ` kernel test robot
2022-07-29 3:49 ` Nicholas Piggin
2022-07-14 16:42 ` kernel test robot
2022-07-14 20:28 ` kernel test robot
2022-07-13 7:06 ` [PATCH v2 07/12] locking/qspinlock: remove arch qspinlock_paravirt.h includes Nicholas Piggin
2022-07-14 13:14 ` kernel test robot
2022-07-14 16:21 ` kernel test robot
2022-07-13 7:07 ` [PATCH v2 08/12] locking/qspinlock: stop renaming queued_spin_lock_slowpath to native_queued_spin_lock_slowpath Nicholas Piggin
2022-07-13 7:07 ` [PATCH v2 09/12] locking/qspinlock: rename __pv_init_lock_hash to pv_spinlocks_init Nicholas Piggin
2022-07-13 7:07 ` Nicholas Piggin [this message]
2022-07-13 7:07 ` [PATCH v2 11/12] locking/qspinlock: separate pv_wait_node from the non-paravirt path Nicholas Piggin
2022-07-13 7:07 ` [PATCH v2 12/12] locking/qspinlock: simplify pv_wait_head_or_lock calling scheme Nicholas Piggin
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