From: Gleb Natapov <gleb@redhat.com>
To: "Joji Mekkattuparamban (joji)" <joji@cisco.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
kvm@vger.kernel.org, mtosatti@redhat.com
Subject: Re: [Qemu-devel] Para-Virtualized Clock Usage
Date: Tue, 23 Apr 2013 08:52:16 +0300 [thread overview]
Message-ID: <20130423055215.GA12401@redhat.com> (raw)
In-Reply-To: <375D787373987F47B9BF5BA875F1ED8818450330@xmb-rcd-x04.cisco.com>
On Mon, Apr 22, 2013 at 04:58:01PM +0000, Joji Mekkattuparamban (joji) wrote:
> Greetings,
>
> I have a SMP guest application, running on the 2.6.27 Linux kernel. The application, originally written for bare metal, makes extensive use of the TSC, by directly invoking rdtsc from the user space for timestamp purposes. While running on KVM (RHEL version 6.3), we are running into TSC issues on some hardware. As a solution, I am considering migrating to the pvclock. I am wondering if there is an example for migrating from TSC to the pvclock. Any pointers?
>
Wrong list, you should ask KVM (copied). Recent kernels have pvclock
vdso support which means that gettimeofday() uses it without entering
the kernel. Marcelo?
--
Gleb.
WARNING: multiple messages have this Message-ID (diff)
From: Gleb Natapov <gleb@redhat.com>
To: "Joji Mekkattuparamban (joji)" <joji@cisco.com>
Cc: mtosatti@redhat.com,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Para-Virtualized Clock Usage
Date: Tue, 23 Apr 2013 08:52:16 +0300 [thread overview]
Message-ID: <20130423055215.GA12401@redhat.com> (raw)
In-Reply-To: <375D787373987F47B9BF5BA875F1ED8818450330@xmb-rcd-x04.cisco.com>
On Mon, Apr 22, 2013 at 04:58:01PM +0000, Joji Mekkattuparamban (joji) wrote:
> Greetings,
>
> I have a SMP guest application, running on the 2.6.27 Linux kernel. The application, originally written for bare metal, makes extensive use of the TSC, by directly invoking rdtsc from the user space for timestamp purposes. While running on KVM (RHEL version 6.3), we are running into TSC issues on some hardware. As a solution, I am considering migrating to the pvclock. I am wondering if there is an example for migrating from TSC to the pvclock. Any pointers?
>
Wrong list, you should ask KVM (copied). Recent kernels have pvclock
vdso support which means that gettimeofday() uses it without entering
the kernel. Marcelo?
--
Gleb.
next prev parent reply other threads:[~2013-04-23 5:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-22 16:58 [Qemu-devel] Para-Virtualized Clock Usage Joji Mekkattuparamban (joji)
2013-04-23 5:52 ` Gleb Natapov [this message]
2013-04-23 5:52 ` Gleb Natapov
2013-04-24 8:27 ` Marcelo Tosatti
2013-04-25 0:28 ` Joji Mekkattuparamban (joji)
2013-04-25 0:28 ` [Qemu-devel] " Joji Mekkattuparamban (joji)
2013-04-25 6:57 ` Gleb Natapov
2013-05-15 20:40 ` Joji Mekkattuparamban (joji)
2013-05-15 20:40 ` Joji Mekkattuparamban (joji)
2013-05-16 8:37 ` Gleb Natapov
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