Re: mutex contention for the query cache

[Frazer Clement]

Jonas Oreland wrote:
> MARK CALLAGHAN wrote:
>   
>> On Fri, Jul 4, 2008 at 11:31 AM, Brian Aker <brian@stripped> wrote:
>>     
>>> Hi!
>>>
>>> On Jul 4, 2008, at 7:44 AM, MARK CALLAGHAN wrote:
>>>
>>>       
>>>> I fear that some of the hardware we are to be offered won't meet the
>>>> needs of the software we have deployed and we will all end up buying
>>>>         
>>> If you end up with multi-core board with multi-processors, if you can
>>> disable cores you can get a bit more performance. Crazy? Yeah, but it
>>> happens to be where the main branch is today.
>>>       
>> There is a Stonebraker research project on an OLTP engine called
>> H-store that partitions data so that one core gets each partition.
>> Locking is not an issue at that point. MySQL Cluster could approximate
>> that deployment model.
>>     
>
> interestingly enough, our ndbmtd version 2 already uses that model.
>
> advertising: goal for it to be functional end of august and usable by end of the
> year
>
> fyi 1: ndbmtd is multi-threaded variant of ndbd
> fyi 2: we already have a ndbmtd version 1, that currently use 3 threads and approx. 2
> cores
> fyi 3: ndbmtd version 2, will be able to utilize 6 threads, and hopefully approx. 6
> cores
> fyi 4: how a future version 3 will look like is not yet determined, we will first
> evaluate how version 2 performs...
>        but the 2 "big" alternatives are roughly
>        1) increase 6 to a bigger number, but keep the 1-thread only operates on a
> subset of data
>        2) allow several threads to operated on same data, introducing ordinary locks
What are the disadvantages of 1)?
> fyi on current ndbmtd internals:
> - threads communicate internally using messages (like it does distributed)
> - all messages are passed using single-reader-single-writer fifo-queues, i.e *no*
> locks
>
> /jonas
>
>   

-- 
Frazer Clement, Software Engineer, MySQL Cluster 
Sun Microsystems - www.mysql.com
Office: Reading, UK

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