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Don't discard the first number so quickly.

For example, say we use a timeout mechanism for the daemon running
inside namespaces to avoid using too much memory with a daemon in
every namespace.  That means we'll pay the startup cost repeatedly but
in a way that amortizes it down.

Even if it is really a one time cost, then if you collect enough
samples then the outlier won't have much affect on the mean anyway.
I'd say keep it in there.

Carl

On Mon, Mar 24, 2014 at 2:04 AM, Miguel Angel Ajo <majopela at redhat.com> wrote:
>
>
> It's the first call starting the daemon / loading config files, etc?,
>
> May be that first sample should be discarded from the mean for all processes
> (it's an outlier value).
>
>
>
>
> On 03/21/2014 05:32 PM, Yuriy Taraday wrote:
>>
>> On Fri, Mar 21, 2014 at 2:01 PM, Thierry Carrez <thierry at openstack.org
>> <mailto:thierry at openstack.org>> wrote:
>>
>>     Yuriy Taraday wrote:
>>      > Benchmark included showed on my machine these numbers (average
>>     over 100
>>      > iterations):
>>      >
>>      > Running 'ip a':
>>      >                                               ip a :   4.565ms
>>      >                                          sudo ip a :  13.744ms
>>      >                            sudo rootwrap conf ip a : 102.571ms
>>      >                                 daemon.run('ip a') :   8.973ms
>>      > Running 'ip netns exec bench_ns ip a':
>>      >                   sudo ip netns exec bench_ns ip a : 162.098ms
>>      >     sudo rootwrap conf ip netns exec bench_ns ip a : 268.115ms
>>      >          daemon.run('ip netns exec bench_ns ip a') : 129.876ms
>>      >
>>      > So it looks like running daemon is actually faster than running
>>     "sudo".
>>
>>     That's pretty good! However I fear that the extremely simplistic
>> filter
>>     rule file you fed on the benchmark is affecting numbers. Could you
>> post
>>     results from a realistic setup (like same command, but with all the
>>     filter files normally found on a devstack host ?)
>>
>>
>> I don't have a devstack host at hands but I gathered all filters from
>> Nova, Cinder and Neutron and got this:
>>          method          :    min       avg       max       dev
>>                     ip a :   3.741ms   4.443ms   7.356ms 500.660us
>>                sudo ip a :  11.165ms  13.739ms  32.326ms   2.643ms
>> sudo rootwrap conf ip a : 100.814ms 125.701ms 169.048ms  16.265ms
>>       daemon.run('ip a') :   6.032ms   8.895ms 172.287ms  16.521ms
>>
>> Then I switched back to one file and got:
>>          method          :    min       avg       max       dev
>>                     ip a :   4.176ms   4.976ms  22.910ms   1.821ms
>>                sudo ip a :  13.240ms  14.730ms  21.793ms   1.382ms
>> sudo rootwrap conf ip a :  79.834ms 104.586ms 145.070ms  15.063ms
>>       daemon.run('ip a') :   5.062ms   8.427ms 160.799ms  15.493ms
>>
>> There is a difference but it looks like it's because of config files
>> parsing, not applying filters themselves.
>>
>> --
>>
>> Kind regards, Yuriy.
>>
>>
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>
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