From: Thomas Gleixner <tglx@linutronix.de>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@amacapital.net>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
devel@linuxdriverproject.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support
Date: Tue, 14 Feb 2017 15:56:08 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1702141552360.3635@nanos> (raw)
In-Reply-To: <20170214124408.25931-1-vkuznets@redhat.com>
On Tue, 14 Feb 2017, Vitaly Kuznetsov wrote:
> Hi,
>
> while we're still waiting for a definitive ACK from Microsoft that the
> algorithm is good for SMP case (as we can't prevent the code in vdso from
> migrating between CPUs) I'd like to send v2 with some modifications to keep
> the discussion going.
Migration is irrelevant. The TSC page is guest global so updates will
happen on some (random) host CPU and therefor you need the usual barriers
like we have them in our seqcounts unless an access to the sequence will
trap into the host, which would defeat the whole purpose of the TSC page.
Thanks,
tglx
next prev parent reply other threads:[~2017-02-14 14:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 12:44 [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support Vitaly Kuznetsov
2017-02-14 12:44 ` [PATCH v2 1/3] x86/hyperv: implement hv_get_tsc_page() Vitaly Kuznetsov
2017-02-14 12:44 ` [PATCH v2 2/3] x86/hyperv: move TSC reading method to asm/mshyperv.h Vitaly Kuznetsov
2017-02-14 12:44 ` [PATCH v2 3/3] x86/vdso: Add VCLOCK_HVCLOCK vDSO clock read method Vitaly Kuznetsov
2017-02-14 14:46 ` [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support KY Srinivasan via Virtualization
2017-02-14 14:56 ` Thomas Gleixner [this message]
2017-02-14 15:50 ` Vitaly Kuznetsov
2017-02-14 17:34 ` Andy Lutomirski
2017-02-15 14:01 ` Vitaly Kuznetsov
2017-02-16 17:50 ` Thomas Gleixner
2017-02-17 10:14 ` Vitaly Kuznetsov
[not found] ` <87tw7txgx9.fsf@vitty.brq.redhat.com>
2017-02-17 10:35 ` Thomas Gleixner
2017-02-17 17:02 ` Andy Lutomirski
[not found] ` <CALCETrXB8CufQujLAg6bbq=DGAMUE293CF7L4Kp+mCSoNWyuBg@mail.gmail.com>
2017-02-17 17:55 ` Thomas Gleixner
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