From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Kogan <alex.kogan@oracle.com>,
linux@armlinux.org.uk, mingo@redhat.com, will.deacon@arm.com,
arnd@arndb.de, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de,
hpa@zytor.com, x86@kernel.org, steven.sistare@oracle.com,
daniel.m.jordan@oracle.com, dave.dice@oracle.com,
rahul.x.yadav@oracle.com
Subject: Re: [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
Date: Wed, 3 Apr 2019 13:40:19 -0400 [thread overview]
Message-ID: <063622f7-6aab-9824-afce-ea5de103e1f6@redhat.com> (raw)
In-Reply-To: <20190403171635.GM4038@hirez.programming.kicks-ass.net>
On 04/03/2019 01:16 PM, Peter Zijlstra wrote:
> On Wed, Apr 03, 2019 at 12:33:20PM -0400, Waiman Long wrote:
>> static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32
>> val)
>> {
>> if (static_branch_unlikely(&use_numa_spinlock))
>> numa_queued_spin_lock_slowpath(lock, val);
>> else
>> native_queued_spin_lock_slowpath(lock, val);
>> }
> That's horrible for the exact reason you state.
>
>> Alternatively, we can also call numa_queued_spin_lock_slowpath() in
>> native_queued_spin_lock_slowpath() if we don't want to increase the code
>> size of spinlock call sites.
> Yeah, still don't much like that though, we're littering the fast path
> of that slow path with all sorts of crap.
Yes, I know it is less than ideal, but that is probably the only option
if we don't have static_call or paravirt. On the other hand, I am
perfectly fine with making CNA depends on PARAVIRT_SPINLOCKS for now
until static_call is available.
Cheers,
Longman
next prev parent reply other threads:[~2019-04-03 17:40 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-29 15:20 [PATCH v2 0/5] Add NUMA-awareness to qspinlock Alex Kogan
2019-03-29 15:20 ` [PATCH v2 1/5] locking/qspinlock: Make arch_mcs_spin_unlock_contended more generic Alex Kogan
2019-03-29 15:20 ` [PATCH v2 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2019-03-29 15:20 ` [PATCH v2 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2019-04-01 9:06 ` Peter Zijlstra
2019-04-01 9:33 ` Peter Zijlstra
2019-04-03 15:53 ` Alex Kogan
2019-04-03 16:10 ` Peter Zijlstra
2019-04-01 9:21 ` Peter Zijlstra
2019-04-01 14:36 ` Waiman Long
2019-04-02 9:43 ` Peter Zijlstra
2019-04-03 15:39 ` Alex Kogan
2019-04-03 15:48 ` Waiman Long
2019-04-03 16:01 ` Peter Zijlstra
2019-04-04 5:05 ` Juergen Gross
2019-04-04 9:38 ` Peter Zijlstra
2019-04-04 18:03 ` Waiman Long
2019-06-04 23:21 ` Alex Kogan
2019-06-05 20:40 ` Peter Zijlstra
2019-06-06 15:21 ` Alex Kogan
2019-06-06 15:32 ` Waiman Long
2019-06-06 15:42 ` Waiman Long
2019-04-03 16:33 ` Waiman Long
2019-04-03 17:16 ` Peter Zijlstra
2019-04-03 17:40 ` Waiman Long [this message]
2019-04-04 2:02 ` Hanjun Guo
2019-04-04 3:14 ` Alex Kogan
2019-06-11 4:22 ` liwei (GF)
2019-06-12 4:38 ` Alex Kogan
2019-06-12 15:05 ` Waiman Long
2019-03-29 15:20 ` [PATCH v2 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2019-04-02 10:37 ` Peter Zijlstra
2019-04-03 17:06 ` Alex Kogan
2019-03-29 15:20 ` [PATCH v2 5/5] locking/qspinlock: Introduce the shuffle reduction optimization " Alex Kogan
2019-04-01 9:09 ` [PATCH v2 0/5] Add NUMA-awareness to qspinlock Peter Zijlstra
2019-04-03 17:13 ` Alex Kogan
2019-07-03 11:58 ` Jan Glauber
2019-07-12 8:12 ` Hanjun Guo
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