Re: [Firebird-devel] FB 2.1 64bit and memory usage ??

[Vlad H. <hv...@us...>]

> > > Thanks for the reminder, I had forgot that part of your proposal...
> > >
> > > As I see in windows it will works exactly as I wish, but on linux I saw
> > > it will use SYNC (works as FW = on) so the double caching will still be
> > > in place on linux ?
> >
> >     On posix it will use or O_DIRECT flag (trivial to implement) or
> > posix_fadvise calls (need think more on it).
> >
> >     I still don't know what is better as i can't test it
> 
> O_DIRECT looks well for raw partitions, though not sure will it give some real 
> effect or not. 

    AFAIU it will not use FS cache (or will almost not use it) - exactly what we want.
Am i wrong ?

> Also seems that we must allocate page on sector boundary to 
> make it work. 

    Its already done. Tested in Windows but i guess it will work on Linux too ;)

> What about fadvise... I do not see a good way to change 
> behaviour on the fly in MT system. 

    I think about to call posix_fadvise(POSIX_FADV_DONTNEED and\or 
POSIX_FADV_NOREUSE) for every just read page, i.e. right after read call

Regards,
Vlad