pbxt-discuss team mailing list archive

[MARK CALLAGHAN <mdcallag@xxxxxxxxx>]

Me too. I need to learn more about the different files used by PBXT.
What access patterns it uses for the (random, sequential), whether
they use mmap, when are they forced to disk, ...

I have lots of things to learn.

On Fri, Mar 19, 2010 at 10:36 AM, erkan yanar <erkan.yanar@xxxxxxxxxxxxx> wrote:
>
> Moin Mark,
>
> reading your post I actively ignored the tmpfs-thing, sorry.
> The general question about the way PBXT uses file-system-cache still
> stays (for me).
>
>
> erkan
>
>
> btw: It "hard" to comment if not in facebook:)
>
> On Fri, Mar 19, 2010 at 10:17:00AM -0700, MARK CALLAGHAN wrote:
>> I don't think so. I think all engines were dependent to a similar
>> degree on tmpfs and nothing go to use the OS buffer cache.
>>
>> AFAIK, tmpfs files are not doubled-buffered in the OS buffer cache. I
>> think I learned this from reading lkml, but I don't mind citations
>> that state otherwise.
>>
>> So, each fetch of a MyISAM row must get all columns and read from the
>> file after doing the primary key index lookup that is likely to hit in
>> the key cache.
>>
>> InnoDB is should do reads from tmpfs for most queries as the table
>> data doesn't fit in the InnoDB buffer cache.
>>
>> I only set two of the my.cnf settings for PBXT and don't know if that
>> was sufficient to keep it from caching too much.
>>
>> On Fri, Mar 19, 2010 at 9:13 AM, erkan yanar <erkan.yanar@xxxxxxxxxxxxx> wrote:
>> >
>> > Moin,
>> >
>> > I enjoy it seeing PBXT gaining more publicity \o/
>> > (http://www.facebook.com/note.php?note_id=378043115932)
>> >
>> > I wonder if PBXT benefits as much as MyISAM from filesystemcache?
>> > Reading the post I think MyISAM is better configured on that machine
>> > than InnoDB, because MyISAM benefits a lot from the filesystemcache.
>> > And now I wonder about best practice for PBXT.
>> >
>> >
>> > regards
>> > erkan
>> >
>> >
>> >
>> >
>> > --
>> > über den grenzen muß die freiheit wohl wolkenlos sein
>> >
>> > _______________________________________________
>> > Mailing list: https://launchpad.net/~pbxt-discuss
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>> >
>>
>>
>>
>> --
>> Mark Callaghan
>> mdcallag@xxxxxxxxx
>
> --
> über den grenzen muß die freiheit wohl wolkenlos sein
>



-- 
Mark Callaghan
mdcallag@xxxxxxxxx