From: Eric Dumazet <eric.dumazet@gmail.com>
To: Michel Lespinasse <walken@google.com>
Cc: paulmck@linux.vnet.ibm.com, Rik van Riel <riel@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
David Howells <dhowells@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Eric Dumazet <edumazet@google.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Manfred Spraul <manfred@colorfullife.com>,
linux-kernel@vger.kernel.org, john.stultz@linaro.org
Subject: Re: [RFC PATCH 1/6] kernel: implement queue spinlock API
Date: Thu, 07 Feb 2013 16:03:54 -0800 [thread overview]
Message-ID: <1360281834.28557.73.camel@edumazet-glaptop> (raw)
In-Reply-To: <CANN689G0N0ynSMVcH9CbOFgL_mLSswOBx5yBzPBag0AO9fk8+A@mail.gmail.com>
On Thu, 2013-02-07 at 15:58 -0800, Michel Lespinasse wrote:
> No, I think that's doable. The trick would be that once a thread
> acquires the lock, the only remaining use of the node is to receive
> the 'next' pointer if/when another thread starts contending for the
> lock. So if the lock state would need to distinguish between a lock
> that is currently locked but not contended (the next value would then
> be NULL), and a lock that is currently locked and contended (the
> lock->next value is the node that goes after the current lock owner)
>
It adds yet another memory write to store the node pointer in the
lock...
I suspect it's going to increase false sharing.
next prev parent reply other threads:[~2013-02-08 0:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 23:13 [RFC PATCH 0/6] fast queue spinlocks Michel Lespinasse
2013-01-22 23:13 ` [RFC PATCH 1/6] kernel: implement queue spinlock API Michel Lespinasse
2013-02-07 22:34 ` Paul E. McKenney
2013-02-07 22:56 ` Eric Dumazet
2013-02-07 23:53 ` Paul E. McKenney
2013-02-07 23:58 ` Michel Lespinasse
2013-02-08 0:03 ` Eric Dumazet [this message]
2013-02-08 0:40 ` Paul E. McKenney
2013-02-08 3:48 ` Michel Lespinasse
2013-02-08 4:36 ` Paul E. McKenney
2013-02-08 5:03 ` Paul E. McKenney
2013-02-08 5:11 ` Michel Lespinasse
2013-02-08 16:17 ` Paul E. McKenney
2013-02-07 23:14 ` John Stultz
2013-02-08 0:35 ` Michel Lespinasse
2013-01-22 23:13 ` [RFC PATCH 2/6] net: convert qdisc busylock to use " Michel Lespinasse
2013-01-22 23:13 ` [RFC PATCH 3/6] ipc: convert ipc objects " Michel Lespinasse
2013-01-22 23:13 ` [RFC PATCH 4/6] kernel: faster queue spinlock implementation Michel Lespinasse
2013-01-23 21:55 ` Rik van Riel
2013-01-23 23:52 ` Michel Lespinasse
2013-01-24 0:18 ` Eric Dumazet
2013-01-25 20:30 ` [RFC PATCH 7/6] kernel: document fast queue spinlocks Rik van Riel
2013-01-22 23:13 ` [RFC PATCH 5/6] net: qdisc busylock updates to account for queue spinlock api change Michel Lespinasse
2013-01-22 23:13 ` [RFC PATCH 6/6] ipc: object locking " Michel Lespinasse
2013-01-22 23:17 ` [RFC PATCH 0/6] fast queue spinlocks Michel Lespinasse
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