Re: [OSDL][BENCHMARK] Database results 2.4 versus 2.5

[Andrew Morton]

Cliff White <[e-mail]> wrote:
>
> > So it sounds like DBT2 is stabilised now, and producing repeatable results? 
> > That's excellent.
> Thanks. the kit's available off Sourceforge now, and we'll have STP version 
> up Mondayish. 

OK.  My utter database ignorance was an
insurmountable-within-two-hour-attention-span problem when I tried to set up
dbt1.

> > So either the I/O scheduler is doing a better job, or the VM page
> > replacement decisions are agreeable for this load.
> 
> Okay. Is there something we could do that would point at one or the other?

Different combinations of working set and physical memory will tell us.

Also, when we have a lot of vmstat/etc traces available we can decide how I/O
bound it is, and whether we need to look at upping the request queue sizes. 
Which is something which we can now do, and which could easily make a
difference here.

But we'll have to get you onto at least 2.5.58 for that ;)

> would a smaller memory database (say 2GB instead of 4GB ) really show you
> anything interesting on a 4GB system, since there's so little pressure? 

Yes, that would be interesting.  We're dealing with single points in
twenty-seven-dimensional space.  Tweaking input parameter individually helps
one gain an understanding of what is going on.