From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: "André Almeida" <andrealmeid@igalia.com>,
"Darren Hart" <dvhart@infradead.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"Ingo Molnar" <mingo@redhat.com>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Valentin Schneider" <vschneid@redhat.com>,
"Waiman Long" <longman@redhat.com>
Subject: Re: [PATCH 2/3] futex: Use RCU-based per-CPU reference counting instead of rcuref_t
Date: Tue, 8 Jul 2025 08:51:24 +0200 [thread overview]
Message-ID: <20250708065124.DtoAH-O1@linutronix.de> (raw)
In-Reply-To: <20250707143623.70325-3-bigeasy@linutronix.de>
On 2025-07-07 16:36:22 [+0200], To linux-kernel@vger.kernel.org wrote:
> From: Peter Zijlstra <peterz@infradead.org>
>
> The use of rcuref_t for reference counting introduces a performance bottleneck
> when accessed concurrently by multiple threads during futex operations.
just folded this bit after kernel test robot complained:
diff --git a/include/linux/futex.h b/include/linux/futex.h
index cd773febd497b..9e9750f049805 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -113,7 +113,7 @@ static inline int futex_hash_allocate_default(void)
return 0;
}
static inline int futex_hash_free(struct mm_struct *mm) { return 0; }
-static inline void futex_mm_init(struct mm_struct *mm) { }
+static inline int futex_mm_init(struct mm_struct *mm) { return 0; }
#endif
Sebastian
next prev parent reply other threads:[~2025-07-08 6:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-07 14:36 [PATCH 0/3] futex: Use RCU-based per-CPU reference counting Sebastian Andrzej Siewior
2025-07-07 14:36 ` [PATCH 1/3] selftests/futex: Adapt the private hash test to RCU related changes Sebastian Andrzej Siewior
2025-07-08 7:41 ` Peter Zijlstra
2025-07-08 8:01 ` Sebastian Andrzej Siewior
2025-07-10 8:08 ` Sebastian Andrzej Siewior
2025-07-07 14:36 ` [PATCH 2/3] futex: Use RCU-based per-CPU reference counting instead of rcuref_t Sebastian Andrzej Siewior
2025-07-08 6:51 ` Sebastian Andrzej Siewior [this message]
2025-07-08 8:56 ` Hillf Danton
2025-07-08 9:16 ` Sebastian Andrzej Siewior
2025-07-08 12:01 ` Hillf Danton
2025-07-08 13:15 ` Sebastian Andrzej Siewior
2025-07-08 22:00 ` Hillf Danton
2025-07-08 13:09 ` Sebastian Andrzej Siewior
2025-07-08 13:43 ` Waiman Long
2025-07-08 13:47 ` Sebastian Andrzej Siewior
2025-07-08 19:06 ` Peter Zijlstra
2025-07-10 15:58 ` Waiman Long
2025-07-07 14:36 ` [PATCH 3/3] futex: Make futex_private_hash_get() static Sebastian Andrzej Siewior
2025-07-08 7:50 ` [PATCH 0/3] futex: Use RCU-based per-CPU reference counting Peter Zijlstra
2025-07-08 8:02 ` Sebastian Andrzej Siewior
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