From: "David S. Ahern" <daahern@cisco.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Ulrich Obergfell <uobergfe@redhat.com>,
kvm@vger.kernel.org, glommer@redhat.com, zamsden@redhat.com,
avi@redhat.com, mtosatti@redhat.com
Subject: Re: [RFC 0/4] KVM in-kernel PM Timer implementation
Date: Tue, 14 Dec 2010 12:54:50 -0700 [thread overview]
Message-ID: <4D07CB8A.8060600@cisco.com> (raw)
In-Reply-To: <4D07CA3C.2010108@codemonkey.ws>
On 12/14/10 12:49, Anthony Liguori wrote:
> But that doesn't tell you what the impact is in real world workloads.
> Before we start pushing all device emulation into the kernel, we need to
> quantify how often gettimeofday() is really called in real workloads.
The workload that inspired that example program at its current max load
calls gtod upwards of 1000 times per second. The overhead of
gettimeofday was the biggest factor when comparing performance to bare
metal and esx. That's why I wrote the test program --- boils a complex
product/program to a single system call.
David
>
> Regards,
>
> Anthony Liguori
>
>> What's the relative speed of the in-kernel pmtimer compared to the PIT?
>>
>> David
>>
>
next prev parent reply other threads:[~2010-12-14 19:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <344060531.680691292328457867.JavaMail.root@zmail07.collab.prod.int.phx2.redhat.com>
2010-12-14 12:09 ` [RFC 0/4] KVM in-kernel PM Timer implementation Ulrich Obergfell
2010-12-14 13:34 ` Avi Kivity
2010-12-14 13:40 ` Glauber Costa
2010-12-14 13:49 ` Avi Kivity
2010-12-14 13:52 ` Gleb Natapov
2010-12-14 15:32 ` Anthony Liguori
2010-12-14 15:38 ` Avi Kivity
2010-12-14 16:04 ` Anthony Liguori
2010-12-15 9:33 ` Avi Kivity
2010-12-14 15:29 ` Anthony Liguori
2010-12-14 18:00 ` David S. Ahern
2010-12-14 19:49 ` Anthony Liguori
2010-12-14 19:54 ` David S. Ahern [this message]
2010-12-14 21:46 ` Anthony Liguori
2010-12-14 23:59 ` David S. Ahern
[not found] <953393305.700721292337871455.JavaMail.root@zmail07.collab.prod.int.phx2.redhat.com>
2010-12-14 14:44 ` Ulrich Obergfell
2010-12-14 15:12 ` Avi Kivity
[not found] <1956121317.795411292413874075.JavaMail.root@zmail07.collab.prod.int.phx2.redhat.com>
2010-12-15 11:53 ` Ulrich Obergfell
2012-02-21 18:10 ` Peter Lieven
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