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From: Eran Rom <eranr@il.ibm.com>
To: kvm@vger.kernel.org
Subject: guest gettimeofday behavior
Date: Thu, 25 Jun 2009 13:25:17 +0000 (UTC)	[thread overview]
Message-ID: <loom.20090625T130343-552@post.gmane.org> (raw)

Hi All,
Am a newbie (to kvm, linux kernel, git, etc.) so apologize in advance for
missing/inaccurate info.
I am experiencing inconsistent behavior of guest gettimeofday, described below.
I have seen prior reference to the problem, however, it was not clear whether
the issue was solved or not and where.

Below is a description of my setup and the behavior I see.
Another question is whether oprofile with timer mode would suffer from the same
problem?

Otherwise I saw that kvm-85 has "generic performance counter msr handling", does
this mean that oprofile can be executed without the timer mode?

Thanks very much,
Eran

Setup:
Guest 32 bit ubuntu with 2.6.27 kernel
Host 64 bit Suse 10.2 with 2.6.27 kernel
1 quadcore Intel Xeon CPU
I am not sure about the kvm userspace code version.
Used git to create a repository, and then did
git checkout kvm-updates-2.6.27 (is that fixed in time?)

Behavior:
Running a code doing:
t1 = gettimeofday
t2 = gettimeofday
while t2-t1 < 5 minutes {
    sleep(1)
    t2 = gettimeofday
}

Ran it 10 times, each time in a 'newly launched' VM, halting it after the test.
8 out of 10 times the wall clock showed 5 minutes
1 time 4 minutes and 40 seconds
1 time 0 seconds


             reply	other threads:[~2009-06-25 13:25 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-25 13:25 Eran Rom [this message]
2009-06-28  8:58 ` guest gettimeofday behavior Dor Laor
2009-06-29 19:11   ` Eran Rom
2009-06-30  6:54     ` Avi Kivity
2009-06-30  7:48       ` Eran Rom
2009-07-06  8:24         ` Eran Rom
2009-07-07  9:58           ` Eran Rom
2009-07-07 20:12             ` Marcelo Tosatti
2009-07-08 11:51               ` Glauber Costa
2009-07-08 14:07                 ` Eran Rom
2009-07-13  7:55                 ` Eran Rom
2009-07-16  6:24                   ` Eran Rom
2009-06-28 10:45 ` Avi Kivity

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