RE: [Xen-devel] xm speed

["James Harper" <JamesH@xxxxxxxxxxxxxxxx>]

To do a very simple test I created a little script that does 'time xm
list' 6 times. Here's the output:

Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Domain-0           0      123    0  r----    198.7
gaia2              1        0    0  -b---     59.8    9601

real    0m9.403s
user    0m1.030s
sys     0m0.080s
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Domain-0           0      123    0  r----    200.0
gaia2              1        0    0  -b---     59.8    9601

real    0m9.997s
user    0m0.980s
sys     0m0.130s
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Domain-0           0      123    0  r----    201.4
gaia2              1        0    0  -b---     59.8    9601

real    0m9.999s
user    0m0.990s
sys     0m0.140s
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Domain-0           0      123    0  r----    202.7
gaia2              1        0    0  -b---     59.8    9601

real    0m9.999s
user    0m1.040s
sys     0m0.090s
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Domain-0           0      123    0  r----    204.0
gaia2              1        0    0  -b---     59.8    9601

real    0m9.998s
user    0m0.990s
sys     0m0.120s
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Domain-0           0      123    0  r----    205.3
gaia2              1        0    0  -b---     59.8    9601

real    0m9.998s
user    0m1.040s
sys     0m0.100s

It's closer to 10 seconds as you can see. After I type 'xm list', it
takes about 5 seconds for the heading to appear, and then roughly 2
seconds per domain. Load under Domain-0 is almost 0.

Another Proliant 1600 I have that is running xen has 2x550Mhz CPU's and
runs much better... roughly 3 seconds from typing 'xm list' to getting
output, and all the output rolls past pretty quick (4 domains on that
one).

The domain gaia2 is actually destroyed in the output above, it just
doesn't know it. Testing iscsi and it went into a spin logging bulk
stuff to the console. I find killing a domain in that state doesn't work
properly and I have to reboot Dom0 to get xend functioning properly
again.

James
 
> -----Original Message-----
> From: Ian Pratt [mailto:Ian.Pratt@xxxxxxxxxxxx]
> Sent: Friday, 10 September 2004 22:55
> To: James Harper
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxxx; Ian.Pratt@xxxxxxxxxxxx
> Subject: Re: [Xen-devel] xm speed
> 
> > I'm waiting about 2 seconds from typing 'xm list' and for something
to
> > appear. Is this normal? The machine is fairly old, it's a Compaq
> > Proliant 1600 with a single CPU running at 350Mhz. It's hardware
RAID
> > but that is pretty slow too.
> 
> If you look at the output of 'xm list' does the CPU time consumed
> by dom0 go up by 2s every time?
> 
> Is dom0 competing for CPU0 with a bunch of other busy domains?
> 
> On our 2.4GHz Xeon machines, I've noticed that running 'xm list'
> causes the amount of CPU consumed by dom0 to go up by around
> 100ms, which is quite a staggering amount given what it's
> actually doing. Python isn't the most efficient of languages, and
> we are doing a HTTP RPC between xm and xend, but this level of
> resource usage has always rather surprised me.
> 
> I guess we could use one of the python profiling tools to find
> out where the overhead is. Since this is all 'control plane' we
> haven't made any effort to make it efficient and have
> concentrated on flexibility. It it starts becoming a bottleneck
> it may be necessary to selectively recode bits in C.
> 
> Ian
> 
> 



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