From: Paolo Bonzini <pbonzini@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>,
Marcelo Tosatti <mtosatti@redhat.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
kvm list <kvm@vger.kernel.org>, Gleb Natapov <gleb@kernel.org>
Subject: Re: [RFC 2/2] x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader
Date: Wed, 07 Jan 2015 06:41:58 +0100 [thread overview]
Message-ID: <54ACC726.80904@redhat.com> (raw)
In-Reply-To: <CALCETrXzJkxbUsVgPbKNpBdp32yf=0M=RfseX=u7Mg2Mmsz2VQ@mail.gmail.com>
On 06/01/2015 19:26, Andy Lutomirski wrote:
> Don't you stil need:
>
> version++;
> write the rest;
> version++;
>
> with possible smp_wmb() in there to keep the compiler from messing around?
No, see my other reply.
Separating the version write is a real bug, but that should be all that
it's needed.
> Also, if you do this, can you also make setting and clearing
> STABLE_BIT properly atomic across all vCPUs? Or at least do something
> like setting it last and clearing it first on vPCU 0?
That would be nice if you want to make the pvclock area fit in a single
page. However, it would have to be a separate flag bit, or a separate
CPUID feature.
Paolo
next prev parent reply other threads:[~2015-01-07 5:41 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-23 0:39 [RFC 0/2] x86, vdso, pvclock: Cleanups and speedups Andy Lutomirski
2014-12-23 0:39 ` [RFC 1/2] x86, vdso: Use asm volatile in __getcpu Andy Lutomirski
2014-12-23 0:39 ` Andy Lutomirski
2014-12-23 0:39 ` [RFC 2/2] x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader Andy Lutomirski
2014-12-23 10:28 ` [Xen-devel] " David Vrabel
2014-12-23 10:28 ` David Vrabel
2014-12-23 15:14 ` Boris Ostrovsky
2014-12-23 15:14 ` [Xen-devel] " Boris Ostrovsky
2014-12-23 15:14 ` Paolo Bonzini
2014-12-23 15:25 ` Boris Ostrovsky
2014-12-23 15:25 ` Boris Ostrovsky
2014-12-23 15:14 ` Paolo Bonzini
2014-12-24 21:30 ` David Matlack
2014-12-24 21:43 ` Andy Lutomirski
2014-12-24 21:43 ` Andy Lutomirski
2014-12-24 21:30 ` David Matlack
2015-01-05 15:25 ` Marcelo Tosatti
2015-01-05 15:25 ` Marcelo Tosatti
2015-01-05 18:56 ` Andy Lutomirski
2015-01-05 19:17 ` Marcelo Tosatti
2015-01-05 19:17 ` Marcelo Tosatti
2015-01-05 22:38 ` Andy Lutomirski
2015-01-05 22:48 ` Marcelo Tosatti
2015-01-05 22:48 ` Marcelo Tosatti
2015-01-05 22:53 ` Andy Lutomirski
2015-01-05 22:53 ` Andy Lutomirski
2015-01-06 8:42 ` Paolo Bonzini
2015-01-06 8:42 ` Paolo Bonzini
2015-01-06 12:01 ` Paolo Bonzini
2015-01-06 16:56 ` Andy Lutomirski
2015-01-06 16:56 ` Andy Lutomirski
2015-01-06 18:13 ` Marcelo Tosatti
2015-01-06 18:13 ` Marcelo Tosatti
2015-01-06 18:26 ` Andy Lutomirski
2015-01-06 18:26 ` Andy Lutomirski
2015-01-06 18:45 ` Marcelo Tosatti
2015-01-06 18:45 ` Marcelo Tosatti
2015-01-06 19:49 ` Andy Lutomirski
2015-01-06 19:49 ` Andy Lutomirski
2015-01-06 20:20 ` Marcelo Tosatti
2015-01-06 21:54 ` Andy Lutomirski
2015-01-06 21:54 ` Andy Lutomirski
2015-01-06 20:20 ` Marcelo Tosatti
2015-01-08 22:31 ` Marcelo Tosatti
2015-01-08 22:43 ` Andy Lutomirski
2015-02-26 22:46 ` Andy Lutomirski
2015-02-26 22:46 ` Andy Lutomirski
2015-01-08 22:43 ` Andy Lutomirski
2015-01-08 22:31 ` Marcelo Tosatti
2015-01-07 5:41 ` Paolo Bonzini [this message]
2015-01-07 5:41 ` Paolo Bonzini
2015-01-07 5:38 ` Paolo Bonzini
2015-01-07 5:38 ` Paolo Bonzini
2015-01-07 7:18 ` Andy Lutomirski
2015-01-07 7:18 ` Andy Lutomirski
2015-01-07 9:00 ` Paolo Bonzini
2015-01-07 9:00 ` Paolo Bonzini
2015-01-07 14:45 ` Marcelo Tosatti
2015-01-07 14:45 ` Marcelo Tosatti
2015-01-05 22:38 ` Andy Lutomirski
2015-01-06 8:39 ` Paolo Bonzini
2015-01-06 8:39 ` Paolo Bonzini
2015-01-05 22:23 ` Paolo Bonzini
2015-01-05 22:23 ` Paolo Bonzini
2015-01-06 14:35 ` Konrad Rzeszutek Wilk
2015-01-06 14:35 ` [Xen-devel] " Konrad Rzeszutek Wilk
2015-01-05 18:56 ` Andy Lutomirski
2015-01-08 12:51 ` David Vrabel
2015-01-08 12:51 ` [Xen-devel] " David Vrabel
2014-12-23 0:39 ` Andy Lutomirski
2014-12-23 7:21 ` [RFC 0/2] x86, vdso, pvclock: Cleanups and speedups Paolo Bonzini
2014-12-23 8:16 ` Andy Lutomirski
2014-12-23 8:30 ` Paolo Bonzini
2014-12-23 8:30 ` Paolo Bonzini
2014-12-23 8:16 ` Andy Lutomirski
2014-12-23 7:21 ` Paolo Bonzini
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