From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: linux-arch@vger.kernel.org, "Juergen Gross" <jgross@suse.com>,
"Jeremy Fitzhardinge" <jeremy@goop.org>,
x86@kernel.org, kvm@vger.kernel.org,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Pan Xinhui" <xinhui.pan@linux.vnet.ibm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
"Chris Wright" <chrisw@sous-sol.org>,
"Ingo Molnar" <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
xen-devel@lists.xenproject.org,
"Alok Kataria" <akataria@vmware.com>,
"Thomas Gleixner" <tglx@linutronix.de>
Subject: Re: [PATCH 2/2] locking/mutex,rwsem: Reduce vcpu_is_preempted() calling frequency
Date: Wed, 8 Feb 2017 20:05:33 +0100 [thread overview]
Message-ID: <20170208190533.GB6515@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1486576825-17058-2-git-send-email-longman@redhat.com>
On Wed, Feb 08, 2017 at 01:00:25PM -0500, Waiman Long wrote:
> As the vcpu_is_preempted() call is pretty costly compared with other
> checks within mutex_spin_on_owner() and rwsem_spin_on_owner(), they
> are done at a reduce frequency of once every 256 iterations.
That's just disgusting.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: "Jeremy Fitzhardinge" <jeremy@goop.org>,
"Chris Wright" <chrisw@sous-sol.org>,
"Alok Kataria" <akataria@vmware.com>,
"Rusty Russell" <rusty@rustcorp.com.au>,
"Ingo Molnar" <mingo@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-arch@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
xen-devel@lists.xenproject.org, kvm@vger.kernel.org,
"Pan Xinhui" <xinhui.pan@linux.vnet.ibm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Juergen Gross" <jgross@suse.com>
Subject: Re: [PATCH 2/2] locking/mutex,rwsem: Reduce vcpu_is_preempted() calling frequency
Date: Wed, 8 Feb 2017 20:05:33 +0100 [thread overview]
Message-ID: <20170208190533.GB6515@twins.programming.kicks-ass.net> (raw)
Message-ID: <20170208190533.ZOK8PACysi7DhrzQUtsRjpF7dvPpcQLyDn1PVi2ad-Y@z> (raw)
In-Reply-To: <1486576825-17058-2-git-send-email-longman@redhat.com>
On Wed, Feb 08, 2017 at 01:00:25PM -0500, Waiman Long wrote:
> As the vcpu_is_preempted() call is pretty costly compared with other
> checks within mutex_spin_on_owner() and rwsem_spin_on_owner(), they
> are done at a reduce frequency of once every 256 iterations.
That's just disgusting.
next prev parent reply other threads:[~2017-02-08 19:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-08 18:00 [PATCH 1/2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function Waiman Long
2017-02-08 18:00 ` Waiman Long
2017-02-08 18:00 ` [PATCH 2/2] locking/mutex, rwsem: Reduce vcpu_is_preempted() calling frequency Waiman Long
2017-02-08 18:00 ` [PATCH 2/2] locking/mutex,rwsem: " Waiman Long
2017-02-08 19:05 ` Peter Zijlstra [this message]
2017-02-08 19:05 ` Peter Zijlstra
2017-02-08 19:09 ` Waiman Long
2017-02-08 19:09 ` Waiman Long
2017-02-08 19:05 ` [PATCH 1/2] x86/paravirt: Don't make vcpu_is_preempted() a callee-save function Peter Zijlstra
2017-02-08 19:05 ` Peter Zijlstra
2017-02-08 20:17 ` Waiman Long
2017-02-08 20:17 ` Waiman Long
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