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Re: Latency question - #of connections




I'd be doing it and would provide update.

BTW, since the query/sec rate is too low, I doubt if it would show
anything. but would try and update.

Both clients aggregate at a switch and come into my server as a single
10G. So it shouldn't matter from poll() system call perspective. I'm
also thinking of using ftrace to debug it...any other ideas?

Thanks a lot!

On Thu, Feb 5, 2015 at 2:22 PM, Stewart Smith
<stewart@xxxxxxxxxxxxxxxxxx> wrote:
> Learner Study <learner.study@xxxxxxxxx> writes:
>> Setup:
>> MySQL 5.6.16 + thread pool extensions running on 3.18 kernel
>>
>> Two sysbench clients running from different PCs with total of 14k
>> connections, each connection doing 2 select queries per sec.
>>
>> When I specify 7k connections from each client, sysbench shows latency
>> of .3 msec (for both sides)
>>
>> If I run with 13k from one client and 1k from the other, latency comes
>> to .6 msec (for both sides)
>>
>> I get that we are load balancing with 7k so latency improves but any
>> ideas which part of MySQL server I should profile to see which area is
>> messing it up with 13k+1k connection split- could it be poll() call?
>> Or some other kernel area?
>
> does perf show any interesting difference between the two setups?
>

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