From: Radim Krcmar <rkrcmar@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Pankaj Gupta <pagupta@redhat.com>,
Wanpeng Li <kernellwp@gmail.com>,
Eduardo Valentin <eduval@amazon.com>,
Paolo Bonzini <pbonzini@redhat.com>, Matt Wilson <msw@amazon.com>,
Jonathan Corbet <corbet@lwn.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Waiman Long <longman@redhat.com>, kvm <kvm@vger.kernel.org>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
"Jan H . Schoenherr" <jschoenh@amazon.de>,
Anthony Liguori <aliguori@amazon.com>
Subject: Re: [PATCHv3 1/1] locking/qspinlock/x86: Avoid test-and-set when PV_DEDICATED is set
Date: Thu, 9 Nov 2017 17:45:23 +0100 [thread overview]
Message-ID: <20171109164523.GF20859@flask> (raw)
In-Reply-To: <20171109161701.y3eqqrvs5jpg46lr@hirez.programming.kicks-ass.net>
2017-11-09 17:17+0100, Peter Zijlstra:
> On Thu, Nov 09, 2017 at 05:05:36PM +0100, Radim Krcmar wrote:
> > 2017-11-09 10:53-0500, Pankaj Gupta:
> > > 2] PV TLB should also behave as per option PV_DEDICATED for better performance.
> >
> > Right,
>
> Shouldn't KVM do flush_tlb_other() in any case? Not sure how
> PV_DEDICATED can help with that.
It will, the suggestion was based on recent extension of the
flush_tlb_others implementaion, https://lkml.org/lkml/2017/11/8/1146.
PV_TLB_FLUSH allows a guest to set a flush bit instead of sending flush
IPI if the target VCPU is not running. This would be a waste of time
with PV_DEDICATED as all VCPUs are expected to always running.
With PV_DEDICATED, the guest should keep using native_flush_tlb_others.
next prev parent reply other threads:[~2017-11-09 16:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-06 20:26 [PATCHv3 1/1] locking/qspinlock/x86: Avoid test-and-set when PV_DEDICATED is set Eduardo Valentin
2017-11-07 12:23 ` Paolo Bonzini
2017-11-07 12:39 ` Eduardo Valentin
2017-11-07 12:43 ` Paolo Bonzini
2017-11-08 8:45 ` Eduardo Valentin
2017-11-08 17:36 ` Radim Krčmář
2017-11-09 8:55 ` Eduardo Valentin
2017-11-09 14:17 ` Radim Krčmář
2017-11-16 4:54 ` Eduardo Valentin
2017-11-27 0:43 ` Wanpeng Li
2017-11-09 12:43 ` Wanpeng Li
2017-11-09 15:53 ` Pankaj Gupta
2017-11-09 16:05 ` Radim Krcmar
2017-11-09 16:17 ` Peter Zijlstra
2017-11-09 16:37 ` Pankaj Gupta
2017-11-09 16:45 ` Radim Krcmar [this message]
2017-11-09 17:12 ` Peter Zijlstra
2017-11-09 17:15 ` Peter Zijlstra
2017-11-09 17:28 ` Peter Zijlstra
2017-11-09 17:35 ` Radim Krcmar
2017-11-10 2:07 ` Wanpeng Li
2017-11-10 7:59 ` Peter Zijlstra
2017-11-10 8:04 ` Wanpeng Li
2017-11-09 17:31 ` Radim Krcmar
2017-11-09 16:00 ` Radim Krcmar
2017-11-10 6:07 ` Wanpeng Li
2017-11-10 8:19 ` Paolo Bonzini
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