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Latency question - #of connections




Hello MySQL experts,

I am new to MySQL and am seeing following behavior

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?

Thanks in advance for my pointers...
Martin

PS: I hear that the same thing when run on kernel 2.6.32 doesn't show
this bad latency witj 13+1 split...yet to be confirmed though

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