On 6/16/2018 9:34 PM, ED Fochler wrote:
>> On 2018, Jun 15, at 9:06 AM, Bowie Bailey <bowie_bai...@buc.com> wrote:
>> The CPUs were not busy.  That's what I was confused about.  I would have
>> expected to see a bottleneck at some point, but nothing seemed to be
>> busy.  The CPUs were all at or below 20% and iowait was close to 0 most
>> of the time.  I'm not sure how I would determine if the loopback was
>> saturated.
> 20% loaded with 6 or more cores would be a single thread running full speed 
> on one core.  A single task may not stay on one core, it may get moved around 
> enough that it doesn't appear that any of the cores are heavily loaded. 
> Doubly true if you have hyperthreading which causes additional CPU shuffling.
> I think you ran into single thread compression performance, plus any of the 
> normal process, network, and IO latency that would compound with everything 
> being on one machine.  That sounds about right to me.  First backups are 
> slow.  SSH probably wouldn't have made any difference at that speed.

No, only 2 cores on this machine.

I have another big local backup that's been running all weekend.  I am
trying sudo/rsync rather than rsyncd or ssh/rsync this time.  This
directory has millions of small files (and is even bigger than the first
one), so I expect it to take longer.

This time, I'm seeing higher IO-wait numbers:

%Cpu0  :  0.0 us,  1.7 sy,  0.0 ni,  5.7 id, 92.6 wa,  0.0 hi,  0.0 si, 
0.0 st
%Cpu1  :  0.3 us,  0.7 sy,  0.0 ni, 86.3 id, 12.4 wa,  0.0 hi,  0.3 si, 
0.0 st

But I don't see high cpu usage.  The IO-wait seems to come and go.  It
alternates with mostly idle periods:

%Cpu0  :  3.0 us,  0.7 sy,  0.0 ni, 96.3 id,  0.0 wa,  0.0 hi,  0.0 si, 
0.0 st
%Cpu1  :  5.0 us,  2.0 sy,  0.0 ni, 92.3 id,  0.7 wa,  0.0 hi,  0.0 si, 
0.0 st

Neither cpu seems to go higher than 6%.

Once this one finishes, I'll have a first round of full backups for all
of the large hosts.  Hopefully, the backup times will be a bit more
reasonable after that.


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