Upgrade to dual-core (Pentium D) processor - Does it worth it?

Hello!

We have a server running FreeBSD 5.4 i386 (which we plan to
upgrade to 
6.1) with a single Pentium 4 2.8GHz processor without SMP
kernel.
This machine basically serves web pages that may or may not
use MySQL 
server (also run in this server).
Usually, we have low usage and load average is ~ 0.2 which
is ok, but 
sometimes, one single process (e.g., mysqld) begins to use
all CPU 
cycles, loading up the system and leading the other smaller
processes 
(in terms of CPU usage) to have a high response time.
As this server's motherboard doesn't support an additional
processor, we 
are wondering whether a Pentium D processor (830) might help
to minimize 
this problem.
In our understanding, one core would be busy with mysqld for
example, 
while the other one would be free to handle other processes
like httpd 
and serve pages that don't even need mysql resources.
Is this correct? Did someone have similiar (successful or
unsuccessful) 
experiences?

Thank you in advance,
Tobias.
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Here's an article you might be interested in..


http://www.overclockers.com.au/article.php?id=489587

-Mike


On Fri, 14 Jul 2006, Tobias P. Santos wrote:

> Hello!
>
> We have a server running FreeBSD 5.4 i386 (which we
plan to upgrade to 6.1) 
> with a single Pentium 4 2.8GHz processor without SMP
kernel.
> This machine basically serves web pages that may or may
not use MySQL server 
> (also run in this server).
> Usually, we have low usage and load average is ~ 0.2
which is ok, but 
> sometimes, one single process (e.g., mysqld) begins to
use all CPU cycles, 
> loading up the system and leading the other smaller
processes (in terms of 
> CPU usage) to have a high response time.
> As this server's motherboard doesn't support an
additional processor, we are 
> wondering whether a Pentium D processor (830) might
help to minimize this 
> problem.
> In our understanding, one core would be busy with
mysqld for example, while 
> the other one would be free to handle other processes
like httpd and serve 
> pages that don't even need mysql resources.
> Is this correct? Did someone have similiar (successful
or unsuccessful) 
> experiences?
>
> Thank you in advance,
> Tobias.
> _______________________________________________
> freebsd-performancefreebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-p
erformance
> To unsubscribe, send any mail to 
> "freebsd-performance-unsubscribefreebsd.org"
>

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On 07/14/06 11:52, Tobias P. Santos wrote:
> Hello!
> 
> We have a server running FreeBSD 5.4 i386 (which we
plan to upgrade to 
> 6.1) with a single Pentium 4 2.8GHz processor without
SMP kernel.
> This machine basically serves web pages that may or may
not use MySQL 
> server (also run in this server).
> Usually, we have low usage and load average is ~ 0.2
which is ok, but 
> sometimes, one single process (e.g., mysqld) begins to
use all CPU 
> cycles, loading up the system and leading the other
smaller processes 
> (in terms of CPU usage) to have a high response time.
> As this server's motherboard doesn't support an
additional processor, we 
> are wondering whether a Pentium D processor (830) might
help to minimize 
> this problem.
> In our understanding, one core would be busy with
mysqld for example, 
> while the other one would be free to handle other
processes like httpd 
> and serve pages that don't even need mysql resources.
> Is this correct? Did someone have similiar (successful
or unsuccessful) 
> experiences?


This isn't a clear cut yes/no situation I don't think, but
for mysqld, 
there's a lot of tuning you could probably do to make the
cpu time drop 
and free up more cycles for other processes.  There's been
discussions 
in the past on this list about mysql, but if you have
already done all 
the optimizations that you can with mysql (with indexes and
such for 
instance), then the extra processor would definitely allow
the other 
non-database blocked web pages to be served, as long as you
aren't 
actually IO bound somewhere.  I don't know how much memory
you have in 
the current machine, but adding more might be a good quick
upgrade (that 
is fairly cheap probably).

Eric


-- 
------------------------------------------------------------
------------
Eric Anderson        Sr. Systems Administrator       
Centaur Technology
Anything that works is better than anything that doesn't.
------------------------------------------------------------
------------
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On Jul 14, 2006, at 12:52 PM, Tobias P. Santos wrote:
> As this server's motherboard doesn't support an
additional  
> processor, we are wondering whether a Pentium D
processor (830)  
> might help to minimize this problem.
> In our understanding, one core would be busy with
mysqld for  
> example, while the other one would be free to handle
other  
> processes like httpd and serve pages that don't even
need mysql  
> resources.
> Is this correct? Did someone have similiar (successful
or  
> unsuccessful) experiences?

Yes, in particular, the preforking design that Apache uses  
distributes very well amoungst multiple CPUs.  There is some
overhead  
from using SMP, you might get better performance by
separating your  
workload into two machines, one dedicated to Apache and one
dedicated  
to your MySQL database, but upgrading to a dual-core CPU is
cheaper...


-- 
-Chuck

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