memory used by btt

memory used by btt

[Ming Zhang]

Hi 

I am now using btt to analyze a 700MB trace data and it always run oom
in my 2GB ram laptop. it also eat 2GB swap as well. Any idea why btt
need so many memory?

ps, why we always need double in the code, can float fit the bill as
well?

Ming

-- 
   Ming Zhang <mzhang AT ibrix.com>
   www.ibrix.com       
   978-670-7400 x 145
   http://blackmagic02881.wordpress.com/

   

Re: memory used by btt

[Alan D. Brunelle]

Ming Zhang wrote:
> Hi 
>
> I am now using btt to analyze a 700MB trace data and it always run oom
> in my 2GB ram laptop. it also eat 2GB swap as well. Any idea why btt
> need so many memory?
>   

Well, BTT builds trees based upon outstanding IO traces. That could 
indicate that BTT is having a hard time dealing with your data - I find 
that sometimes the kernel does weird things, causing strange IO trees 
being built that BTT can't put back together. I've got some multi-GB 
sized binary files that I've handled, let me see what the memory 
footprint is for those...


> ps, why we always need double in the code, can float fit the bill as
> well?
>   

Probably could, but I'm not too sure about some of the conversions done 
with LBAs. I can look into that if need be.

Alan

> Ming
>
>   

Re: memory used by btt

[Ming Zhang]

On Mon, 2007-03-26 at 12:17 -0400, Alan D. Brunelle wrote:
> Ming Zhang wrote:
> > Hi 
> >
> > I am now using btt to analyze a 700MB trace data and it always run oom
> > in my 2GB ram laptop. it also eat 2GB swap as well. Any idea why btt
> > need so many memory?
> >   
> 
> Well, BTT builds trees based upon outstanding IO traces. That could 
> indicate that BTT is having a hard time dealing with your data - I find 
> that sometimes the kernel does weird things, causing strange IO trees 
> being built that BTT can't put back together. I've got some multi-GB 
> sized binary files that I've handled, let me see what the memory 
> footprint is for those...
> 
> 
> > ps, why we always need double in the code, can float fit the bill as
> > well?
> >   
> 
> Probably could, but I'm not too sure about some of the conversions done 
> with LBAs. I can look into that if need be.

i did a quick check, changing to float will not have much help on that
footprint. double is not used in some key data structures.

> 
> Alan
> 
> > Ming
> >
> >   
> 
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