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On 03/23/2012 01:26 PM, Mark Washenberger wrote:
>
>
> "Johannes Erdfelt"<johannes at erdfelt.com>  said:
>
>>
>> MySQL isn't exactly slow and Nova doesn't have particularly large
>> tables. It looks like the slowness is coming from the network and how
>> many queries are being made.
>>
>> Avoiding joins would mean even more queries, which looks like it would
>> slow it down even further.
>>
>
> This is exactly what I saw in my profiling. More complex queries did
> still seem to take longer than less complex ones, but it was a second
> order effect compared to the overall volume of queries.
>
> I'm not sure that network was the culprit though, since my ping
> roundtrip time was small relative to the wall time I measured for each
> nova.db.api call.

How much data would the queries return, and how long between queries? 
One "networking" thing that might come into play would be slow start 
after idle - if the query returns are > INITCWND (either 3 or 10 
segments depending on which kernel) and they are separated by at least 
one RTO (or is it RTT?) then they will hit slow start each time.  Now, 
the extent to which that matters is a function of how large the return 
is, and it is only adding RTTs so it wouldn't be minutes, but it could 
add up a bit I suppose.

rick jones