The Phenom / PhenomII memory controller: ganged vs unganged mode benchmarked

Written by Gionatan Danti on . Posted in Hardware analysis

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Real world test: Sysbench MySQL benchmark

Another very common server role is a MySQL database server. The database will prefer the ganged mode or the unganged one? Let's see, starting with a simple (read only) test and four concurrent client threads:

MySQL simple benchmark - four concurrent client threads

The ganged mode is about 2% faster. However, remember that such a low difference can be explained by a measurement error.

How about the 256 thread test?

MySQL simple benchmark - 512 concurrent client threads

This time the unganged mode wins, but as the difference is under 1% I will consider round a tie.

Now, let's examine the more complex, transactional (read / write) scenario:

MySQL complex benchmark - four concurrent client threads

With four threads, the unganged mode seems to have a rather low 2% advantage, so I will consider this test a tie.

MySQL complex benchmark - 512 concurrent client threads

In the 512 thread test the unganged mode give us a <1% speedup. So, we have hardly any news: it was a tie.

Comments   

 
#1 Julián Fernández 2012-07-21 00:40
This was quality reading. Thanks mate.
 
 
#2 Iz 2013-01-24 23:14
Thank you for sharing these insights. I found them most useful indeed.
 
 
#3 asd 2014-03-26 19:17
Your graphs are misleading. You should ALWAYS show the full range in any graph (i.e. starting at 0 value), so the magnitude of the gains can be seen at first glance. This is statistics 101.
At least you labeled your axis.
 
 
#4 Gionatan Danti 2014-03-26 19:29
Quoting asd:
Your graphs are misleading. You should ALWAYS show the full range in any graph (i.e. starting at 0 value), so the magnitude of the gains can be seen at first glance. This is statistics 101.
At least you labeled your axis.


Yes, you are right.

When the differences are small, old OpenOffice Calc versions tend to create graphs which don't start from 0.

I realized that only after the graph were published, and I preferred to leave them unmodified.

Regards.
 
 
#5 Jay 2016-06-06 07:09
Thank you for this in-depth piece. It was the best explanation I've come across, and I've been looking for a while. :)
 
 
#6 SvenBent 2016-08-20 16:11
Ncie read through but really wish the bar graphs wasn;t made so misleading. now i have t ohave a huge focus on et he X-axis to get a indication of how big the diffrent really is.

really bad to not start your graphs at 0
 

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