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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>,
Ashok Raj <ashok.raj@intel.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
Tony Luck <tony.luck@intel.com>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Arjan van de Ven <arjan@infradead.org>,
Alan Cox <alan@linux.intel.com>
Cc: x86 <x86@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/15] x86/split_lock: Enable #AC exception for split locked accesses
Date: Tue, 15 May 2018 08:10:59 -0700 [thread overview]
Message-ID: <ef39e053-ad81-2058-f66c-037f90b53516@intel.com> (raw)
In-Reply-To: <1526323945-211107-1-git-send-email-fenghua.yu@intel.com>
On 05/14/2018 11:52 AM, Fenghua Yu wrote:
> When executing an atomic instruction, sometimes the data access crosses
> the cache line boundary. This causes performance degradation. Intel
> introduces mechanism to detect such split lock issue via alignment check
> fault.
This is still a pretty sparse description.
Could you describe the performance degradation? Why is this not a
"doctor it hurts when I do that" situation?
Could you also give us *some* idea which CPUs this will show up on? Is
it a one-off feature, or will it be available widely?
> Since kernel doesn't know when SMI comes, it's impossible for kernel
> to disable split lock #AC before entering SMI. So SMI handler may
> inherit kernel's split lock setting and kernel tester may end up
> debug split lock issues in SMI.
What's a "kernel tester"?
next prev parent reply other threads:[~2018-05-15 15:11 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-14 18:52 [PATCH 0/15] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2018-05-14 18:52 ` [PATCH 01/15] x86/split_lock: Add CONFIG and enumerate #AC exception for split locked access feature Fenghua Yu
2018-05-15 15:36 ` Dave Hansen
2018-05-15 15:41 ` Fenghua Yu
2018-05-15 15:54 ` Dave Hansen
2018-05-14 18:52 ` [PATCH 02/15] x86/split_lock: Set up #AC exception for split locked accesses Fenghua Yu
2018-05-14 18:52 ` [PATCH 03/15] x86/split_lock: Handle #AC exception for split lock in kernel mode Fenghua Yu
2018-05-15 15:51 ` Dave Hansen
2018-05-15 16:35 ` Luck, Tony
2018-05-15 17:21 ` Fenghua Yu
2018-05-16 16:44 ` Dave Hansen
2018-05-16 21:35 ` Fenghua Yu
2018-05-14 18:52 ` [PATCH 04/15] x86/split_lock: Use non locked bit set instruction in set_cpu_cap Fenghua Yu
2018-05-14 18:52 ` [PATCH 05/15] x86/split_lock: Use non atomic set and clear bit instructions to clear cpufeature Fenghua Yu
2018-05-14 18:52 ` [PATCH 06/15] x86/split_lock: Save #AC setting for split lock in BIOS in boot time and restore the setting in reboot Fenghua Yu
2018-05-14 18:52 ` [PATCH 07/15] x86/split_lock: Handle suspend/hibernate and resume Fenghua Yu
2018-05-14 21:42 ` Rafael J. Wysocki
2018-05-14 18:52 ` [PATCH 08/15] x86/split_lock: Set split lock during EFI runtime service Fenghua Yu
2018-05-14 18:52 ` [PATCH 09/15] x86/split_lock: Explicitly enable or disable #AC for split locked accesses Fenghua Yu
2018-05-15 16:15 ` Dave Hansen
2018-05-15 17:29 ` Fenghua Yu
2018-05-16 16:37 ` Dave Hansen
2018-05-14 18:52 ` [PATCH 10/15] x86/split_lock: Add a sysfs interface to allow user to enable or disable split lock during run time Fenghua Yu
2018-05-14 18:52 ` [PATCH 11/15] x86/split_lock: Add sysfs interface to control user mode behavior Fenghua Yu
2018-05-14 18:52 ` [PATCH 12/15] x86/split_lock: Add sysfs interface to show and control BIOS split lock setting Fenghua Yu
2018-05-14 18:52 ` [PATCH 13/15] x86/split_lock: Trace #AC exception for split lock Fenghua Yu
2018-05-14 18:52 ` [PATCH 14/15] x86/split_lock: Add CONFIG and testing sysfs interface Fenghua Yu
2018-05-14 18:52 ` [PATCH 15/15] x86/split_lock: Add split lock user space test in selftest Fenghua Yu
2018-05-15 15:10 ` Dave Hansen [this message]
2018-05-15 16:26 ` [PATCH 0/15] x86/split_lock: Enable #AC exception for split locked accesses Alan Cox
2018-05-15 16:30 ` Dave Hansen
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