Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock

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To: Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>
Subject: Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
From: Waiman Long <longman@xxxxxxxxxx>
Date: Thu, 4 Apr 2019 14:03:15 -0400
Cc: Alex Kogan <alex.kogan@xxxxxxxxxx>, linux@xxxxxxxxxxxxxxx, mingo@xxxxxxxxxx, will.deacon@xxxxxxx, arnd@xxxxxxxx, linux-arch@xxxxxxxxxxxxxxx, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, tglx@xxxxxxxxxxxxx, bp@xxxxxxxxx, hpa@xxxxxxxxx, x86@xxxxxxxxxx, steven.sistare@xxxxxxxxxx, daniel.m.jordan@xxxxxxxxxx, dave.dice@xxxxxxxxxx, rahul.x.yadav@xxxxxxxxxx
In-reply-to: <20190404093859.GU4038@hirez.programming.kicks-ass.net>
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Organization: Red Hat
References: <20190329152006.110370-1-alex.kogan@oracle.com> <20190329152006.110370-4-alex.kogan@oracle.com> <60a3a2d8-d222-73aa-2df1-64c9d3fa3241@redhat.com> <20190402094320.GM11158@hirez.programming.kicks-ass.net> <6AEDE4F2-306A-4DF9-9307-9E3517C68A2B@oracle.com> <20190403160112.GK4038@hirez.programming.kicks-ass.net> <faf4ffdd-b0d9-e18b-d394-2d1c19811dc5@suse.com> <20190404093859.GU4038@hirez.programming.kicks-ass.net>
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On 04/04/2019 05:38 AM, Peter Zijlstra wrote:
> On Thu, Apr 04, 2019 at 07:05:24AM +0200, Juergen Gross wrote:
>
>> Without PARAVIRT_SPINLOCK this would be just an alternative() then?
> That could maybe work yes. This is all early enough.

Yes, alternative() should work as it is done before SMP boot. The
slowpath should never be executed before SMP boot.

Cheers,
Longman

References:
- [PATCH v2 0/5] Add NUMA-awareness to qspinlock
  - From: Alex Kogan
- [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Alex Kogan
- Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Waiman Long
- Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Peter Zijlstra
- Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Alex Kogan
- Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Peter Zijlstra
- Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Juergen Gross
- Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
  - From: Peter Zijlstra

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