From: Juergen Gross <jgross@suse.com>
To: Waiman Long <longman@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: jeremy@goop.org, x86@kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, chrisw@sous-sol.org,
mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com,
xen-devel@lists.xenproject.org, akataria@vmware.com,
boris.ostrovsky@oracle.com
Subject: Re: [PATCH v2 1/2] paravirt/locks: use new static key for controlling call of virt_spin_lock()
Date: Wed, 6 Sep 2017 19:33:10 +0200 [thread overview]
Message-ID: <6db11611-3b41-47fe-ec4c-75b1decbc83c@suse.com> (raw)
In-Reply-To: <73d39808-ad47-6d06-89be-034181099408@redhat.com>
On 06/09/17 18:13, Waiman Long wrote:
> On 09/06/2017 12:04 PM, Peter Zijlstra wrote:
>> On Wed, Sep 06, 2017 at 11:49:49AM -0400, Waiman Long wrote:
>>>> #define virt_spin_lock virt_spin_lock
>>>> static inline bool virt_spin_lock(struct qspinlock *lock)
>>>> {
>>>> + if (!static_branch_likely(&virt_spin_lock_key))
>>>> + return false;
>>>> if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
>>>> return false;
>>>>
>> Now native has two NOPs instead of one. Can't we merge these two static
>> branches?
>
>
> I guess we can remove the static_cpu_has() call. Just that any spin_lock
> calls before native_pv_lock_init() will use the virt_spin_lock(). That
> is still OK as the init call is done before SMP starts.
Hmm, right. I'll send V3 in some minutes.
Juergen
next prev parent reply other threads:[~2017-09-06 17:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170906152928.8658-1-jgross@suse.com>
2017-09-06 15:29 ` [PATCH v2 1/2] paravirt/locks: use new static key for controlling call of virt_spin_lock() Juergen Gross
2017-09-06 15:29 ` [PATCH v2 2/2] paravirt,xen: correct xen_nopvspin case Juergen Gross
[not found] ` <20170906152928.8658-2-jgross@suse.com>
2017-09-06 15:49 ` [PATCH v2 1/2] paravirt/locks: use new static key for controlling call of virt_spin_lock() Waiman Long
[not found] ` <a0cf01cf-922a-dbc7-949e-0f87bcdd1ad9@redhat.com>
2017-09-06 16:04 ` Peter Zijlstra
2017-09-06 16:13 ` Waiman Long
[not found] ` <73d39808-ad47-6d06-89be-034181099408@redhat.com>
2017-09-06 17:33 ` Juergen Gross [this message]
[not found] ` <20170906152928.8658-3-jgross@suse.com>
2017-09-06 15:50 ` [PATCH v2 2/2] paravirt,xen: correct xen_nopvspin case Waiman Long
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