Re: why does throughput increase with number of connections even if it exceeds number of processors?

2011-09-06 Thread Andrew Moore
Hong,

What you are seeing is probably your server's ability to keep up with your
benchmark with some comfort. I assume your benchmark isn't completing in a
couple of seconds but would presume that you are not IO bound and all
changes are happening in memory. Its hard to give you 'the' answer as you
haven't provided enough info to work with but in my estimations you aren't
working your machine hard enough. How true to your application is your
benchmark? If you are not expecting an append only workload then you might
be wasting your time merely adding records to a table whcich is what your
benchmark sounds like its doing.

Hth

Andy
On Sep 6, 2011 3:27 AM, Chuntao HONG chuntao.h...@gmail.com wrote:
 Hi,

 I wrote a micro benchmark to test the performance of my MySQL server.
 In the benchmark, which is written in C#, I created several threads,
 each with a connection to the MySQL server, to insert rows into the
 same table. Totally 3200 rows are inserted into the table.

 When I try to vary the number of C# threads I found that the time
 taken to finish the benchmark decreases, thus increasing the
 throughput. The throughput increases almost linearly with the number
 of C# threads, until I reach 100 threads, which is the maximum number
 of connections allowed by my server.

 This is quite unexpected, since the server has only two processors. I
 expect the throughput to grow from one connection to two connections.
 But I don't expect it to grow with more than two connections. Why is
 it the case?

 My Server has one Intel Xeon X3360 CPU with two cores running at
 2.83GHz and 8GB of main memory. It runs Windows Server 2008 R2. The
 MySQL version is 5.5.15 x64 Edition.


 Thanks!

 HONG Chuntao

 --
 MySQL General Mailing List
 For list archives: http://lists.mysql.com/mysql
 To unsubscribe: http://lists.mysql.com/mysql?unsub=eroomy...@gmail.com



Re: Seconds Behind the master 0 but in reality it's over 10 minutes or hours..

2011-09-06 Thread Kristian Davies
On Tue, Sep 6, 2011 at 6:12 AM, Rob Wultsch wult...@gmail.com wrote:
 Hm.

 It seems we have sort of ethernet segment saturation problem.

 A possible bandaid/quick fix is turning on compression for mysql replication.

We've had this exact same issue with a dodgy/overused wan link.

If you are going to turn on compression you'll want to keep an eye on
the CPU usage on the master (works well for us for the moment).

-Kristian

-- 
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe:http://lists.mysql.com/mysql?unsub=arch...@jab.org