From: Waiman Long <waiman.long@hpe.com>
To: Pan Xinhui <xinhui@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
<linuxppc-dev@lists.ozlabs.org>, <linux-kernel@vger.kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Boqun Feng <boqun.feng@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] powerpc: introduce {cmp}xchg for u8 and u16
Date: Wed, 13 Apr 2016 11:53:26 -0400 [thread overview]
Message-ID: <570E6B76.5080306@hpe.com> (raw)
In-Reply-To: <570E2A45.9080702@linux.vnet.ibm.com>
On 04/13/2016 07:15 AM, Pan Xinhui wrote:
> Hello Peter,
>
> On 2016年04月12日 22:30, Peter Zijlstra wrote:
>
>>> I am working on the qspinlock implementation on PPC.
>>> Your and Waiman's patches are so nice. :)
>> Thanks!, last time I looked at PPC spinlocks they could not use things
>> like ticket locks because PPC might be a guest and fairness blows etc..
>>
>> You're making the qspinlock-paravirt thing work on PPC, or doing
>> qspinlock only for bare-metal PPC?
>>
> I am making the both work. :)
> qspinlock works on PPC now. I am preparing the patches and will send them out in next weeks :)
What of performance improvement are you seeing in PPC?
> The paravirt work is a little hard.
> currently, there are pv_wait() and pv_kick(). but only pv_kick has the parameter cpu(who will hold the lock as soon as the lock is unlocked).
> We need parameter cpu(who holds the lock now) in pv_wait,too.
That can be doable to a certain extent. However, if the current lock
holder acquired the lock via the fastpath only. The CPU information is
not logged anywhere. For a contended lock, the information should be there.
Cheers,
Longman
next prev parent reply other threads:[~2016-04-13 15:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 6:41 [PATCH] powerpc: introduce {cmp}xchg for u8 and u16 Pan Xinhui
2016-04-08 7:47 ` Peter Zijlstra
2016-04-10 14:17 ` Pan Xinhui
2016-04-12 14:30 ` Peter Zijlstra
2016-04-13 11:15 ` Pan Xinhui
2016-04-13 15:53 ` Waiman Long [this message]
2016-04-14 8:31 ` Pan Xinhui
2016-04-16 19:43 ` Arnd Bergmann
2016-04-18 10:19 ` Pan Xinhui
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