From: Peter Hurley <peter@hurleysoftware.com>
To: Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arch@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Waiman Long <waiman.long@hp.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Alex Shi <alex.shi@linaro.org>, Andi Kleen <andi@firstfloor.org>,
Michel Lespinasse <walken@google.com>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
Matthew R Wilcox <matthew.r.wilcox@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Rik van Riel <riel@redhat.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
George Spelvin <linux@horizon.com>,
"H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
Aswin Chandramouleeswaran <aswin@hp.com>,
Scott J Norton <scott.norton@hp.com>
Subject: Re: [RFC] Control dependencies
Date: Fri, 22 Nov 2013 12:59:41 -0500 [thread overview]
Message-ID: <528F9B8D.2090806@hurleysoftware.com> (raw)
In-Reply-To: <20131122134630.GQ3866@twins.programming.kicks-ass.net>
On 11/22/2013 08:46 AM, Peter Zijlstra wrote:
> How about the below version?
>
> ---
> --- a/kernel/events/ring_buffer.c
> +++ b/kernel/events/ring_buffer.c
> @@ -61,19 +61,20 @@ static void perf_output_put_handle(struc
> *
> * kernel user
> *
> - * READ ->data_tail READ ->data_head
> - * smp_mb() (A) smp_rmb() (C)
> - * WRITE $data READ $data
> - * smp_wmb() (B) smp_mb() (D)
> - * STORE ->data_head WRITE ->data_tail
> + * if (LOAD ->data_tail) { LOAD ->data_head
> + * (A) smp_rmb() (C)
> + * STORE $data LOAD $data
> + * smp_wmb() (B) smp_mb() (D)
> + * STORE ->data_head STORE ->data_tail
I wasn't subscribed to linux-arch so missed the smp_store_release()
outcome, if there was one.
Are (B) and (D) still slated for changing to STORE.rel semantics,
aka smp_store_release()?
I realize that, for the perf ring buffer, (D) is in userspace but
I'm also interested in non-perf situations where (D) would be in the
kernel.
Regards,
Peter Hurley
WARNING: multiple messages have this Message-ID (diff)
From: Peter Hurley <peter@hurleysoftware.com>
To: Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arch@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Waiman Long <waiman.long@hp.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Alex Shi <alex.shi@linaro.org>, Andi Kleen <andi@firstfloor.org>,
Michel Lespinasse <walken@google.com>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
Matthew R Wilcox <matthew.r.wilcox@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Rik van Riel <riel@redhat.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
George Spelvin <linux@horizon.com>,
"H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
Aswin Chandramouleeswaran <aswin@hp.com>,
Scott J Norton <scott.norton@hp.com>,
"Figo.zhang" <figo1802@gmail.com>
Subject: Re: [RFC] Control dependencies
Date: Fri, 22 Nov 2013 12:59:41 -0500 [thread overview]
Message-ID: <528F9B8D.2090806@hurleysoftware.com> (raw)
Message-ID: <20131122175941.ailMVt-2_BdtygQ3imPjRiem6-Ux8La7Y4H_M1QS9vk@z> (raw)
In-Reply-To: <20131122134630.GQ3866@twins.programming.kicks-ass.net>
On 11/22/2013 08:46 AM, Peter Zijlstra wrote:
> How about the below version?
>
> ---
> --- a/kernel/events/ring_buffer.c
> +++ b/kernel/events/ring_buffer.c
> @@ -61,19 +61,20 @@ static void perf_output_put_handle(struc
> *
> * kernel user
> *
> - * READ ->data_tail READ ->data_head
> - * smp_mb() (A) smp_rmb() (C)
> - * WRITE $data READ $data
> - * smp_wmb() (B) smp_mb() (D)
> - * STORE ->data_head WRITE ->data_tail
> + * if (LOAD ->data_tail) { LOAD ->data_head
> + * (A) smp_rmb() (C)
> + * STORE $data LOAD $data
> + * smp_wmb() (B) smp_mb() (D)
> + * STORE ->data_head STORE ->data_tail
I wasn't subscribed to linux-arch so missed the smp_store_release()
outcome, if there was one.
Are (B) and (D) still slated for changing to STORE.rel semantics,
aka smp_store_release()?
I realize that, for the perf ring buffer, (D) is in userspace but
I'm also interested in non-perf situations where (D) would be in the
kernel.
Regards,
Peter Hurley
next prev parent reply other threads:[~2013-11-22 17:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-21 16:17 [RFC] Control dependencies Peter Zijlstra
2013-11-21 16:17 ` Peter Zijlstra
2013-11-21 18:02 ` Paul E. McKenney
2013-11-21 18:02 ` Paul E. McKenney
2013-11-21 19:28 ` Paul E. McKenney
2013-11-21 19:28 ` Paul E. McKenney
2013-11-22 13:46 ` Peter Zijlstra
2013-11-22 13:46 ` Peter Zijlstra
2013-11-22 17:59 ` Peter Hurley [this message]
2013-11-22 17:59 ` Peter Hurley
2013-11-25 9:42 ` Peter Zijlstra
2013-11-25 9:42 ` Peter Zijlstra
2013-11-22 18:16 ` Paul E. McKenney
2013-11-22 18:16 ` Paul E. McKenney
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