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From: Dave Hansen <dave.hansen@intel.com>
To: Fenghua Yu <fenghua.yu@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
	"H. Peter Anvin" <hpa@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>,
	Rafael Wysocki <rafael.j.wysocki@intel.com>,
	Tony Luck <tony.luck@intel.com>, Alan Cox <alan@linux.intel.com>,
	Ravi V Shankar <ravi.v.shankar@intel.com>,
	Arjan van de Ven <arjan@infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses
Date: Tue, 29 May 2018 09:40:09 -0700	[thread overview]
Message-ID: <b4d3e2d0-dfb1-fa1d-8430-0bcb124063e5@intel.com> (raw)
In-Reply-To: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com>

On 05/27/2018 08:45 AM, Fenghua Yu wrote:
> A split lock is any atomic operation whose operand crosses two cache
> lines. Since the operand spans two cache lines and the operation must
> be atomic, the system locks the bus while the CPU accesses the two cache
> lines.

Could you give us a bit of an idea why this is RFC?  What needs review?
What needs commenting-on?  What is left before you think this can be
merged?  Where would you like Thomas, Ingo, and other reviewers to focus
their attention?

One thing we from Intel can be horrible about is launching in to the
details of the hardware implementation instead of focusing on the
software implications.  For instance, you launch into the details of bus
locks without mentioning key things like:

Split-lock-detection is a new hardware feature that generates
alignment-check (#AC) faults to help detect when badly-aligned atomic
instructions might impact whole-system performance.  These patches are
primarily targeted at application-level issues, but we can also detect
the same issues in the kernel.  There is a significant interaction
between this feature and firmware because firmware may or may not be
prepared for this feature to be enabled.

  parent reply	other threads:[~2018-05-29 16:40 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-27 15:45 [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 01/16] x86/split_lock: Add CONFIG and enumerate #AC exception for split locked access feature Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 02/16] x86/split_lock: Handle #AC exception for split lock in kernel mode Fenghua Yu
2018-06-21 19:46   ` Peter Zijlstra
2018-06-22 10:49   ` Thomas Gleixner
2018-06-22 11:59     ` Thomas Gleixner
2018-06-22 22:41       ` Fenghua Yu
2018-06-22 22:57         ` Thomas Gleixner
2018-06-22 23:03           ` Thomas Gleixner
2018-06-22 23:18       ` Fenghua Yu
2018-06-23  9:08         ` Thomas Gleixner
2018-06-23  4:20     ` Fenghua Yu
2018-06-23  9:17       ` Thomas Gleixner
2018-06-23 15:05         ` Fenghua Yu
2018-06-24  0:55           ` Thomas Gleixner
2018-06-24  1:17             ` Fenghua Yu
2018-06-24  6:43               ` Thomas Gleixner
2018-05-27 15:45 ` [RFC PATCH 03/16] x86/split_lock: Set up #AC exception for split locked accesses on all CPUs Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 04/16] x86/split_lock: Use non locked bit set instruction in set_cpu_cap Fenghua Yu
2018-06-21 19:55   ` Peter Zijlstra
2018-06-21 20:37     ` Thomas Gleixner
2018-06-27 23:35     ` Fenghua Yu
2018-06-28  7:53       ` Thomas Gleixner
2018-06-28 14:23         ` Fenghua Yu
2018-06-28 14:54           ` Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 05/16] x86/split_lock: Use non atomic set and clear bit instructions in clear_cpufeature() Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 06/16] x86/split_lock: Save #AC setting for split lock in firmware in boot time and restore the setting in reboot Fenghua Yu
2018-06-21 19:58   ` Peter Zijlstra
2018-06-22 15:11     ` Alan Cox
2018-06-26  9:05       ` Peter Zijlstra
2018-06-26  9:40         ` Thomas Gleixner
2018-06-26 11:02         ` Alan Cox
2018-06-26 11:31           ` Peter Zijlstra
2018-05-27 15:45 ` [RFC PATCH 07/16] x86/split_lock: Handle suspend/hibernate and resume Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 08/16] x86/split_lock: Set split lock during EFI runtime service Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 09/16] x86/split_lock: Add CONFIG to control #AC for split lock at boot time Fenghua Yu
2018-05-27 15:45 ` [RFC PATCH 10/16] x86/split_lock: Add a debugfs interface to allow user to enable or disable #AC for split lock during run time Fenghua Yu
2018-05-29 18:43   ` Greg KH
2018-05-27 15:46 ` [RFC PATCH 11/16] x86/split_lock: Add CONFIG to control #AC for split lock from kernel at boot time Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 12/16] x86/split_lock: Add a debugfs interface to allow user to change how to handle split lock in kernel mode during run time Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 13/16] x86/split_lock: Add debugfs interface to control user mode behavior Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 14/16] x86/split_lock: Add debugfs interface to show and control firmware setting for split lock Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 15/16] x86/split_lock: Add CONFIG and debugfs interface for testing #AC for split lock in kernel mode Fenghua Yu
2018-05-27 15:46 ` [RFC PATCH 16/16] x86/split_lock: Add user space split lock test in selftest Fenghua Yu
2018-05-29 16:39 ` [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses Dave Hansen
2018-05-29 17:25   ` Fenghua Yu
2018-05-29 17:28     ` Dave Hansen
2018-05-29 17:40       ` Fenghua Yu
2018-05-29 16:40 ` Dave Hansen [this message]
2018-05-29 17:38   ` Fenghua Yu
2018-06-21 20:06   ` Peter Zijlstra
2018-06-21 19:37 ` Peter Zijlstra
2018-06-21 20:18   ` Fenghua Yu
2018-06-21 20:32     ` Thomas Gleixner
2018-06-21 22:00       ` Fenghua Yu
2018-06-21 22:07         ` Peter Zijlstra
2018-06-21 22:08         ` Peter Zijlstra
2018-06-21 22:18           ` Dave Hansen
2018-06-21 22:42             ` Fenghua Yu
2018-06-22  8:11               ` Peter Zijlstra
2018-06-22  9:30               ` Thomas Gleixner
2018-06-21 22:10         ` Peter Zijlstra
2018-06-21 23:05           ` Fenghua Yu
2018-06-22  8:19             ` Peter Zijlstra
2018-06-21 22:11         ` Peter Zijlstra
2018-06-21 22:43           ` Fenghua Yu
2018-06-21 22:13         ` Peter Zijlstra
2018-06-23 18:47           ` Fenghua Yu
2018-06-22  9:18         ` Thomas Gleixner
2018-06-22  9:22         ` Thomas Gleixner
2018-06-22  9:25         ` Thomas Gleixner
2018-06-22  9:28         ` Thomas Gleixner
2018-06-21 20:36     ` Peter Zijlstra

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