Hello Yaniv Kaul:
my comments is below.
Yaniv Kaul wrote:
On 5/18/2009 4:54 AM, Bear Yang wrote:
Hello Yaniv Kaul:
I am understand your means for timedrift testcase.
* give up using ntp to query and sync the clock from guest to host.
my question is below:
1. why we can not using the NTP staff in timedrift test case? Is
there some positive bugs were point on NTP or we found that something
of NTP definite blocked us to using it? Or could you give me what
exact we need give up NTP in timedrift test case?
Just another requirement from the host we do not really need. And a
bit more hassle to configure on Windows. And who knows how to
configure on operating system this-or-that.
Actually, I still have not a clear realize about why not give up NTP in
timedrift test case. just for could not run this mode on windows guest?
Except this NTP have not problem internally to block us to use it? right?
I have working on TimeDrift problem base on KVM for several months, now
you pointed out that we do not need NTP. you really need give me a
reasonable reason or explanation for this at first. because If I give up
NTP, that mean I need rewrite the TimeDrift case. the bug related my
case will be abolished and my work on this will be abolished.
2. for your algorithm:
MeasureHostParams() // don't forget to measure the host's CPU,
memory, I/O and network data - always useful.
while (!enough)
{
RunAnotherVM() // don't forget to call SleepTillVmIsFullyRunning()
ForEachVM // this runs in parallel on the VMs
{
before = TimeOnHost()
RunXMinutesLoadOnGuest(load, minutes) // load can vary -
synthetic CPU, I/O or 'real life' load. Can also vary from VM to VM.
after = TimeOnHost()
drift = after - before
If(drift >= TooMuch) // How much is too much? Could be in
percentage or absolute values.
enough = true
}
}
Why get time from host(TimeOnHost()), why?I think it should be
TimeOnGuest(). Could you kindly tell me the details about how to get
the value of before/after and drift?
I don't need to get the time on the guest. I know I've asked it to run
a load for X minutes. The guest has run that for what it think is X
minutes - but may be X+drift minutes - because its clock drifted. If I
want to know by how much, I need to compare to a reliable source - the
host (or in our case, the test server actually).
Yes, we need get the compare between host clock and guest clock whatever
we useing NTP or not, please tell me how to get this comparison in your
algorithm clearly. and show me how exactly you implement it for the
value(before/after and drift)
We purpose is found out if *Guest* has time drift problem. KVM is full
virtualizaiton technology, guest does not know it running as a guest. so
Why we need add the loaded to Host?
BTW, my script now have the ability to configre option from control file
to running stress testing just for X minutes or X hours?
3. you suggest that the loaded is runing on host is prefer than
running on guest and running several guest on host to make load on
host. right? why? nowadays, I using the stress program which provided
by Lucas just running in guest.
Good, load the guest. But if the host can satisfy the guest's
requirements, it won't be drifting (I hope!). We need to overload a
bit here. The most natural way is with more VMs.
I don't catch your means for your sentence "load the guest. But if the
host can satisfy the guest's requirements, it won't be drifting (I
hope!)." Could you please explain it for me?
4. I also want to know the result that the script works on your
side.Maybe it is more easy to help me understand your algorithm than
read the script.
We'll need to run it. Haven't run it for a while actually.
Y.
thanks for your explanation
Yaniv Kaul wrote:
On 5/15/2009 7:30 PM, bear wrote:
Good morning you all. :)
Lucas:
Very appreciated your help on try...except block implementation. I
am finally understand your means when I read the mail. :(
I modified the timedrift case in several place again.
1. add more comments in script.
2. functional the snippnet of script which get clock resource from
guest and host.
3. using vm.get_command_status replace the sendline API when
complie the stress program in guest area.
If there is something need to be done by me for the script. feel
free just kick me.
Happy weekend.
Hi Bear,
Please drop the NTP stuff. There's no need for it.
Llet me again suggest my algorithm (pseudo-code, of course):
MeasureHostParams() // don't forget to measure the host's CPU,
memory, I/O and network data - always useful.
while (!enough)
{
RunAnotherVM() // don't forget to call SleepTillVmIsFullyRunning()
ForEachVM // this runs in parallel on the VMs
{
before = TimeOnHost()
RunXMinutesLoadOnGuest(load, minutes) // load can vary -
synthetic CPU, I/O or 'real life' load. Can also vary from VM to VM.
after = TimeOnHost()
drift = after - before
If(drift >= TooMuch) // How much is too much? Could be in
percentage or absolute values.
enough = true
}
}
Simple algorithm, works for us, does not require NTP, and loads the
host in the most natural way it will be loaded in real life - by
more VMs.
Slight variations are possible. For example, use the first VM as a
'canary' VM - and measure only on it - the others can do random
load; pin down VM to CPUs; vary the load, the VMs used, and the
time, etc.
HTH,
Y.
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