linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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
Subject: [PATCH 10/13] locking/qspinlock: paravirt use simple trylock in case idx overflows
Date: Tue,  5 Jul 2022 00:38:17 +1000	[thread overview]
Message-ID: <20220704143820.3071004-11-npiggin@gmail.com> (raw)
In-Reply-To: <20220704143820.3071004-1-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 1d5b3443772c..cef0ca7d94e1 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -798,13 +798,8 @@ static inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, bool parav
 	 */
 	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


  parent reply	other threads:[~2022-07-04 14:39 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-04 14:38 [PATCH 00/13] locking/qspinlock: simplify code generation Nicholas Piggin
2022-07-04 14:38 ` [PATCH 01/13] locking/qspinlock: remove pv_node abstraction Nicholas Piggin
2022-07-06 23:23   ` Boqun Feng
2022-07-04 14:38 ` [PATCH 02/13] locking/qspinlock: inline mcs_spinlock functions into qspinlock Nicholas Piggin
2022-07-05 16:57   ` Peter Zijlstra
2022-07-12  0:06     ` Nicholas Piggin
2022-07-04 14:38 ` [PATCH 03/13] locking/qspinlock: split common mcs queueing code into its own function Nicholas Piggin
2022-07-05 17:01   ` Peter Zijlstra
2022-07-12  0:10     ` Nicholas Piggin
2022-07-04 14:38 ` [PATCH 04/13] locking/qspinlock: move pv lock word helpers into qspinlock.c Nicholas Piggin
2022-07-05 19:34   ` Waiman Long
2022-07-12  0:11     ` Nicholas Piggin
2022-07-04 14:38 ` [PATCH 05/13] locking/qspinlock: be less clever with the preprocessor Nicholas Piggin
2022-07-05 17:08   ` Peter Zijlstra
2022-07-12  0:29     ` Nicholas Piggin
2022-07-05 20:02   ` Waiman Long
2022-07-12  0:33     ` Nicholas Piggin
2022-07-04 14:38 ` [PATCH 06/13] locking/qspinlock: merge qspinlock_paravirt.h into qspinlock.c Nicholas Piggin
2022-07-05 17:20   ` Peter Zijlstra
2022-07-05 17:36     ` Peter Zijlstra
2022-07-12  0:46       ` Nicholas Piggin
2022-07-06 13:35     ` Waiman Long
2022-07-06 14:16       ` Peter Zijlstra
2022-07-04 14:38 ` [PATCH 07/13] locking/qspinlock: remove arch qspinlock_paravirt.h includes Nicholas Piggin
2022-07-04 14:38 ` [PATCH 08/13] locking/qspinlock: stop renaming queued_spin_lock_slowpath to native_queued_spin_lock_slowpath Nicholas Piggin
2022-07-05 17:28   ` Peter Zijlstra
2022-07-04 14:38 ` [PATCH 09/13] locking/qspinlock: rename __pv_init_lock_hash to pv_spinlocks_init Nicholas Piggin
2022-07-04 14:38 ` Nicholas Piggin [this message]
2022-07-04 14:38 ` [PATCH 11/13] locking/qspinlock: Use queued_spin_trylock in pv_hybrid_queued_unfair_trylock Nicholas Piggin
2022-07-05 17:31   ` Peter Zijlstra
2022-07-05 20:15   ` Waiman Long
2022-07-12  0:48     ` Nicholas Piggin
2022-07-04 14:38 ` [PATCH 12/13] locking/qspinlock: separate pv_wait_node from the non-paravirt path Nicholas Piggin
2022-07-05 17:34   ` Peter Zijlstra
2022-07-12  0:50     ` Nicholas Piggin
2022-07-04 14:38 ` [PATCH 13/13] locking/qspinlock: simplify pv_wait_head_or_lock calling scheme Nicholas Piggin
2022-07-05 17:59 ` [PATCH 00/13] locking/qspinlock: simplify code generation Peter Zijlstra
2022-07-12  0:56   ` Nicholas Piggin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220704143820.3071004-11-npiggin@gmail.com \
    --to=npiggin@gmail.com \
    --cc=boqun.feng@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=longman@redhat.com \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).