Hi,
Please forgive me if I'm being dumb here... In the case of
'hyperthreading' CPUs (the Xeon), is there an advantage to locking a
process to one of these 'CPUs' (ie half of the hardware chip).
Thanks, noodl
(Apologies Mikael for addressing this message directly to you ear)
On Wed, 2005-02-02 at 23:29 +0100, Mikael Ronström wrote:
> Hi,
>
> 2005-02-02 kl. 20.23 skrev Jim Hoadley:
>
> > Mikael et al. --
> >
> >> Actually in multi-CPU boxes it can be very
> >> beneficial to lock the ndbd process to a CPU (advantegous also from
> >> use of
> >> cache memory and gives very predictable performance) if the OS
> >> supports
> >> such actions.
> >
> > This brings to mind 2 general questions.
> >
> > 1) If I am putting together a 3-node cluster (API and NDB on BOX1, API
> > and NDB
> > on BOX2, MGM on BOX3), how much will it help to buy 2-CPU boxes
> > instead of
> > single CPUs? Worth the added price? These would be something like
> > 3.6GHz Xeon,
> > 4GB RAM and 2 36GB 10k RPM SCSI drives.
> >
>
> For BOX1 and BOX2 it would certainly help, I can't really see any
> reasons why it couldn't more or less double
> the workload you can handle as long as the disks can handle it which I
> presume they would in this case. For
> BOX3 you don't need any second CPU and even the CPU itself could be a
> low-end variant.
>
> > 2) If so, what kind of performance gain, if any, would I get from
> > locking the
> > NDBD process to one of the CPUs?
> >
>
> In this case it would mostly provide better and more predictable
> latency on individual queries whereas overall
> throughput would likely go down since the mysqld process usually
> consumes more CPU power than the ndbd
> process.
>
> Rgrds Mikael
>
> > Thanks in advance!
> >
> > -- Jim Hoadley
> >
> >
> > --- Mikael Ronström <mikael@stripped> wrote:
> >
> >> Hi,
> >>
> >> 2005-02-02 kl. 01.58 skrev Mike Schroeder:
> >>
> >>> I have similar questions:
> >>>
> >>> So if we use dual 64-bit AMD Opterons with 16 GB RAM, will MySQL
> >>> access all 16 GB?
> >>> Has anyone found any point of diminishing returns on the amount of
> >>> memory in a server?
> >>> Which is better: fewer servers with more memory, or more servers with
> >>> less memory?
> >>>
> >>
> >> If the OS is 64-bit the answer is yes, both for the MySQL Server and
> >> for the ndbd processes
> >> in the MySQL Cluster. For a 32 bit OS, the limitation on OS exists as
> >> Marco W. pointed out
> >> below. For ndbd processes Marco W. notes were correct that you can run
> >> several ndbd processes
> >> per box to make use of a memory bigger than 4 GB (my experience is
> >> that
> >> the limit is even 3 GB or
> >> less since the OS uses up some of the virtual memory addresses plus
> >> due
> >> to fragmentation of
> >> virtual memory address space).
> >>
> >> Whether to use fewer servers or more servers is more dependent on the
> >> number of CPU's. One ndbd
> >> can make use of between 1-2 CPU's so if you have a 4-CPU box you need
> >> at least two ndbd or one
> >> ndbd + mysqld to fully utilise the CPU's. It is also a matter of
> >> whether best throughput or lowest latency
> >> is desired. Best throughput is achieved if you allocate around 1 CPU
> >> per ndbd node and best latency
> >> if you have 1.5-2 CPU's allocated to the ndbd process. Actually in
> >> multi-CPU boxes it can be very
> >> beneficial to lock the ndbd process to a CPU (advantegous also from
> >> use
> >> of cache memory and gives
> >> very predictable performance) if the OS supports such actions.
> >>
> >> Rgrds Mikael
> >>
> >>>
> >>>
> >>>
> >>>
> >>> Marco Wertejuk wrote:
> >>>
> >>>> Hey,
> >>>>
> >>>> | What is the limitation of a 32-bit architecture as it
> >>>> | relates to RAM and MySQL Cluster?
> >>>>
> >>>> I actually don't know about how mysql cluster is programmed
> >>>> according to memory usage, but I can tell you that no
> >>>> application can use more than 4GB memory on 32bit x86
> >>>> servers. Redhat enterprise supports more that 4GB using
> >>>> high address memory and em64t technology, but due to
> >>>> how memory configurations above the 32bit address limitations
> >>>> are supported no application can use more than 4GB.
> >>>>
> >>>> Of course you can run 2 4GB memory consuming applications
> >>>> on you 8GB server but this might not work with mysql cluster.
> >>>>
> >>>> You should probably consider using a 4 node cluster where
> >>>> you have 2 groups with each 2 nodes for redundancy and splitting
> the
> >>>> dataset across two servers.
> >>>>
> >>>> I think this will be easier for you at the cost of
> >>>> more hardware and probably more point of failures.
> >>>>
> >>>>
> >>>
> >>> --
> >>> MySQL Cluster Mailing List
> >>> For list archives: http://lists.mysql.com/cluster
> >>> To unsubscribe:
> >>> http://lists.mysql.com/cluster?unsub=1
> >>>
> >>>
> >> Mikael Ronström, Senior Software Architect
> >> MySQL AB, www.mysql.com
> >>
> >> Jumpstart your cluster:
> >> http://www.mysql.com/consulting/packaged/cluster.html
> >>
> >>
> >> --
> >> MySQL Cluster Mailing List
> >> For list archives: http://lists.mysql.com/cluster
> >> To unsubscribe:
> >> http://lists.mysql.com/cluster?unsub=1
> >>
> >>
> >
> >
> >
> >
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> > --
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> >
> Mikael Ronström, Senior Software Architect
> MySQL AB, www.mysql.com
>
> Jumpstart your cluster:
> http://www.mysql.com/consulting/packaged/cluster.html
>
>
