From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Andy Lutomirski <luto@amacapital.net>,
Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>,
"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>
Subject: Re: [RFC 2/2] x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader
Date: Tue, 23 Dec 2014 10:25:49 -0500 [thread overview]
Message-ID: <5499897D.3000904__49316.0769845874$1419348345$gmane$org@oracle.com> (raw)
In-Reply-To: <549986C3.4060807@redhat.com>
On 12/23/2014 10:14 AM, Paolo Bonzini wrote:
>
> On 23/12/2014 16:14, Boris Ostrovsky wrote:
>>> + do {
>>> + version = pvti->version;
>>> +
>>> + /* This is also a read barrier, so we'll read version first. */
>>> + rdtsc_barrier();
>>> + tsc = __native_read_tsc();
>>
>> This will cause VMEXIT on Xen with TSC_MODE_ALWAYS_EMULATE which is
>> used, for example, after guest migrated (unless HW is capable of scaling
>> TSC rate).
> So does the __pvclock_read_cycles this is replacing (via
> pvclock_get_nsec_offset).
Right, I didn't notice that.
-boris
next prev parent reply other threads:[~2014-12-23 15:23 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 15:14 ` [Xen-devel] " Paolo Bonzini
2014-12-23 15:25 ` Boris Ostrovsky [this message]
2014-12-23 15:25 ` Boris Ostrovsky
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 18:56 ` Andy Lutomirski
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 22:53 ` 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 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
2015-01-08 22:43 ` Andy Lutomirski
2015-02-26 22:46 ` Andy Lutomirski
2015-02-26 22:46 ` Andy Lutomirski
2015-01-08 22:31 ` Marcelo Tosatti
2015-01-06 19:49 ` Andy Lutomirski
2015-01-07 5:41 ` Paolo Bonzini
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 22:48 ` 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 ` [Xen-devel] " Konrad Rzeszutek Wilk
2015-01-06 14:35 ` Konrad Rzeszutek Wilk
2015-01-05 15:25 ` Marcelo Tosatti
2015-01-08 12:51 ` [Xen-devel] " David Vrabel
2015-01-08 12:51 ` 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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