Re: [sample] mem_notify v6: usage example

[Andreas Dilger <adilger@sun.com>]

On Feb 10, 2008  01:46 +0900, KOSAKI Motohiro wrote:
> > This really needs to be triggered via a generic kernel event in the
> > final version - I picture glibc having a reservation API and having
> > generic support for freeing such reservations.
> 
> to be honest, I doubt idea of generic reservation framework.
> 
> end up, we hope drop the application cache, not also dataless memory.
> but, automatically drop mechanism only able to drop dataless memory.
> 
> and, many application have own memory management subsystem.
> I afraid to nobody use too complex framework.

Having such notification handled by glibc to free up unused malloc (or
any heap allocations) would be very useful, because even if a program
does "free" there is no guarantee the memory is returned to the kernel.

I think that having a generic reservation framework is too complex, but
hiding the details of /dev/mem_notify from applications is desirable.
A simple wrapper (possibly part of glibc) to return the poll fd, or set
up the signal is enough.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.