From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: linux-arch@vger.kernel.org, Hanjun Guo <guohanjun@huawei.com>,
Arnd Bergmann <arnd@arndb.de>,
dave.dice@oracle.com, Jan Glauber <jglauber@marvell.com>,
x86@kernel.org, Will Deacon <will.deacon@arm.com>,
linux@armlinux.org.uk, linux-kernel@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
hpa@zytor.com, Alex Kogan <alex.kogan@oracle.com>,
Steven Sistare <steven.sistare@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA
Date: Sat, 25 Jan 2020 12:16:07 +0100 [thread overview]
Message-ID: <20200125111607.GV11457@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <714892cd-d96f-4d41-ae8b-d7b7642a6e3c@redhat.com>
On Fri, Jan 24, 2020 at 11:46:53AM -0500, Waiman Long wrote:
> I also thought about that. As you said, it can be hard to guarantee that
> reliable time value can be retrieved in a timely manner across all the
> archs.
Rememer that this code is limited to 64bit archs that have NUMA, my
quick grep says that is limited to:
alpha, arm64, ia64, mips, powerpc, s390, sparc, x86
afaict, x86 is the one with the worst clocks between the lot of them
(with exception of ia64, which has been completely buggered for a while
and nobody cares).
> Even if we can do that, we will introduce latency to important
> tasks or contexts. I like the first approach better.
In general, the kernel has no clues what is actually important.
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next prev parent reply other threads:[~2020-01-25 11:16 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-30 19:40 [PATCH v8 0/5] Add NUMA-awareness to qspinlock Alex Kogan
2019-12-30 19:40 ` [PATCH v8 1/5] locking/qspinlock: Rename mcs lock/unlock macros and make them more generic Alex Kogan
2019-12-30 19:40 ` [PATCH v8 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2019-12-30 19:40 ` [PATCH v8 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2020-01-03 22:14 ` Waiman Long
2020-01-06 15:02 ` Alex Kogan
2020-01-21 13:48 ` Peter Zijlstra
2020-01-21 14:42 ` Peter Zijlstra
2019-12-30 19:40 ` [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2020-01-06 15:33 ` Waiman Long
2020-01-21 13:29 ` Peter Zijlstra
2020-01-21 13:50 ` Peter Zijlstra
2020-01-21 21:19 ` Daniel Bristot de Oliveira
2020-01-21 15:45 ` Waiman Long
[not found] ` <3862F8A1-FF9B-40AD-A88E-2C0BA7AF6F58@oracle.com>
2020-01-24 7:52 ` Peter Zijlstra
2020-01-24 14:42 ` Waiman Long
2020-01-24 15:13 ` Peter Zijlstra
2020-01-24 15:19 ` Waiman Long
[not found] ` <8D3AFB47-B595-418C-9568-08780DDC58FF@oracle.com>
[not found] ` <714892cd-d96f-4d41-ae8b-d7b7642a6e3c@redhat.com>
2020-01-25 11:16 ` Peter Zijlstra [this message]
[not found] ` <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com>
[not found] ` <45660873-731a-a810-8c57-1a5a19d266b4@redhat.com>
2020-01-24 18:51 ` Waiman Long
2020-01-25 11:20 ` Peter Zijlstra
2020-01-25 19:57 ` Waiman Long
[not found] ` <693E6287-E37C-4C5D-BE33-B3D813BE505D@oracle.com>
2020-01-24 21:12 ` Waiman Long
2020-01-24 21:27 ` Alex Kogan
2020-01-25 0:38 ` Waiman Long
2020-01-25 11:19 ` Peter Zijlstra
2020-01-30 22:05 ` Alex Kogan
2020-02-03 13:45 ` Peter Zijlstra
2020-02-03 14:59 ` Waiman Long
2020-02-03 15:28 ` Peter Zijlstra
2020-02-03 15:47 ` Waiman Long
[not found] ` <83762715-F68C-42DF-9B41-C4C48DF6762F@oracle.com>
2020-02-04 17:27 ` Peter Zijlstra
2020-02-04 17:39 ` Waiman Long
2020-02-04 17:53 ` Alex Kogan
2019-12-30 19:40 ` [PATCH v8 5/5] locking/qspinlock: Introduce the shuffle reduction optimization " Alex Kogan
2020-01-22 9:56 ` Peter Zijlstra
2020-01-06 15:48 ` [PATCH v8 0/5] Add NUMA-awareness to qspinlock Waiman Long
2020-01-08 5:09 ` Shijith Thotton
2020-01-21 9:21 ` Shijith Thotton
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