Re: [RFC PATCH-tip v2 1/6] locking/osq: Make lock/unlock proper acquire/release barrier
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
- To: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
- Subject: Re: [RFC PATCH-tip v2 1/6] locking/osq: Make lock/unlock proper acquire/release barrier
- From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
- Date: Wed, 15 Jun 2016 11:27:24 -0700
- Cc: Waiman Long <Waiman.Long@xxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx, linux-alpha@xxxxxxxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linux-s390@xxxxxxxxxxxxxxx, linux-arch@xxxxxxxxxxxxxxx, Jason Low <jason.low2@xxxxxx>, Dave Chinner <david@xxxxxxxxxxxxx>, Scott J Norton <scott.norton@xxxxxxx>, Douglas Hatch <doug.hatch@xxxxxxx>
- In-reply-to: <20160615171250.GO30921@twins.programming.kicks-ass.net>
- List-id: <linux-ia64.vger.kernel.org>
- References: <1465944489-43440-1-git-send-email-Waiman.Long@hpe.com> <1465944489-43440-2-git-send-email-Waiman.Long@hpe.com> <20160615165659.GC2094@linux-80c1.suse> <20160615171250.GO30921@twins.programming.kicks-ass.net>
- User-agent: Mutt/1.5.24 (2015-08-30)
On Wed, 15 Jun 2016, Peter Zijlstra wrote:
In any case, its fairly simple to cure, just add
smp_acquire__after_ctrl_dep() at the end. If we bail because
need_resched() we don't need the acquire I think.
I was just considering this for your smp_cond_acquire/smp_cond_load_acquire
rework, so yeah I guess an smp_acquire__after_ctrl_dep would be a nice
compromise.
However, I was always under the impression that races with node->locked were
rather harmless (as indicated in the mentioned commit) -- which is why ->locked
are simple load/stores, with the exception of the unqueueing -- but yeah, that's
not even paired.
Thanks,
Davidlohr
--
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
[Index of Archives]
[Linux Kernel]
[Sparc Linux]
[DCCP]
[Linux ARM]
[Yosemite News]
[Linux SCSI]
[Linux x86_64]
[Linux for Ham Radio]