From: Alex Kogan <alex.kogan@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux@armlinux.org.uk, mingo@redhat.com, will.deacon@arm.com,
arnd@arndb.de, longman@redhat.com, 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, guohanjun@huawei.com,
jglauber@marvell.com, steven.sistare@oracle.com,
daniel.m.jordan@oracle.com, dave.dice@oracle.com,
rahul.x.yadav@oracle.com
Subject: Re: [PATCH v3 2/5] locking/qspinlock: Refactor the qspinlock slow path
Date: Tue, 16 Jul 2019 10:53:02 -0400 [thread overview]
Message-ID: <9D5B6F33-6003-4CCA-BBE5-998B5A679B9C@oracle.com> (raw)
In-Reply-To: <20190716102034.GN3419@hirez.programming.kicks-ass.net>
On Jul 16, 2019, at 6:20 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Mon, Jul 15, 2019 at 03:25:33PM -0400, Alex Kogan wrote:
>
>> +/*
>> + * set_locked_empty_mcs - Try to set the spinlock value to _Q_LOCKED_VAL,
>> + * and by doing that unlock the MCS lock when its waiting queue is empty
>> + * @lock: Pointer to queued spinlock structure
>> + * @val: Current value of the lock
>> + * @node: Pointer to the MCS node of the lock holder
>> + *
>> + * *,*,* -> 0,0,1
>> + */
>> +static __always_inline bool __set_locked_empty_mcs(struct qspinlock *lock,
>> + u32 val,
>> + struct mcs_spinlock *node)
>> +{
>> + return atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL);
>> +}
>
> That name is nonsense. It should be something like:
>
> static __always_inline bool __try_clear_tail(…)
We already have set_locked(), so I was trying to convey the fact that we are
doing the same here, but only when the MCS chain is empty.
I can use __try_clear_tail() instead.
>
>
>> +/*
>> + * pass_mcs_lock - pass the MCS lock to the next waiter
>> + * @node: Pointer to the MCS node of the lock holder
>> + * @next: Pointer to the MCS node of the first waiter in the MCS queue
>> + */
>> +static __always_inline void __pass_mcs_lock(struct mcs_spinlock *node,
>> + struct mcs_spinlock *next)
>> +{
>> + arch_mcs_spin_unlock_contended(&next->locked, 1);
>> +}
>
> I'm not entirely happy with that name either; but it's not horrible like
> the other one. Why not mcs_spin_unlock_contended() ?
Sure, I can use mcs_spin_unlock_contended() instead.
Thanks,
— Alex
next prev parent reply other threads:[~2019-07-16 14:54 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 19:25 [PATCH v3 0/5] Add NUMA-awareness to qspinlock Alex Kogan
2019-07-15 19:25 ` [PATCH v3 1/5] locking/qspinlock: Make arch_mcs_spin_unlock_contended more generic Alex Kogan
2019-07-16 10:23 ` Peter Zijlstra
2019-07-15 19:25 ` [PATCH v3 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2019-07-16 10:20 ` Peter Zijlstra
2019-07-16 14:53 ` Alex Kogan [this message]
2019-07-16 15:58 ` Peter Zijlstra
2019-07-15 19:25 ` [PATCH v3 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2019-07-15 21:30 ` Waiman Long
2019-07-16 11:04 ` Peter Zijlstra
2019-07-16 14:26 ` Alex Kogan
2019-07-16 14:44 ` Waiman Long
[not found] ` <aa73b86d-902a-bb6f-d372-8645c8299a6d@redhat.com>
[not found] ` <C1C55A40-FDB1-43B5-B551-F9B8BE776DF8@oracle.com>
2019-07-16 14:50 ` Waiman Long
2019-07-17 17:44 ` Alex Kogan
2019-07-17 17:58 ` Waiman Long
2019-07-16 11:05 ` Peter Zijlstra
2019-07-16 14:30 ` Alex Kogan
2019-07-16 15:50 ` Peter Zijlstra
2019-07-16 17:19 ` Alex Kogan
2019-07-16 18:47 ` Peter Zijlstra
2019-07-17 8:39 ` Peter Zijlstra
2019-07-17 8:59 ` Peter Zijlstra
2019-07-17 14:52 ` Alex Kogan
[not found] ` <FFC2D45A-24B3-40E1-ABBB-1D696E830B23@oracle.com>
2019-07-17 15:09 ` Peter Zijlstra
2019-07-17 2:16 ` Waiman Long
2019-07-17 7:44 ` Peter Zijlstra
2019-07-17 13:35 ` Waiman Long
2019-07-17 14:42 ` Alex Kogan
2019-07-15 19:25 ` [PATCH v3 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2019-07-16 15:59 ` Peter Zijlstra
2019-07-15 19:25 ` [PATCH v3 5/5] locking/qspinlock: Introduce the shuffle reduction optimization " Alex Kogan
2019-07-16 11:47 ` [PATCH v3 0/5] Add NUMA-awareness to qspinlock Nicholas Piggin
[not found] ` <7D29555E-8F72-4EDD-8A87-B1A59C3945A6@oracle.com>
2019-07-16 23:07 ` Nicholas Piggin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9D5B6F33-6003-4CCA-BBE5-998B5A679B9C@oracle.com \
--to=alex.kogan@oracle.com \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=daniel.m.jordan@oracle.com \
--cc=dave.dice@oracle.com \
--cc=guohanjun@huawei.com \
--cc=hpa@zytor.com \
--cc=jglauber@marvell.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=longman@redhat.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rahul.x.yadav@oracle.com \
--cc=steven.sistare@oracle.com \
--cc=tglx@linutronix.de \
--cc=will.deacon@arm.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).