Re: Fw: two 2.6.13-rc3-mm3 oddities

[Dipankar Sarma <dipankar@in.ibm.com>]

On Mon, Aug 08, 2005 at 10:25:59AM -0700, Andrew Morton wrote:
> Dipankar Sarma <dipankar@in.ibm.com> wrote:
> >
> > > But: IIRC the counters were moved to the ctor/dtor for performance 
> > > reasons, I'd guess mbligh ran into cache line trashing on the 
> > > filp_count_lock spinlock with reaim or something like that.
> > 
> > Ah, so the whole idea was to inc/dec nr_files less often so
> > that we reduce contention on filp_count_lock, right ? This however
> > causes skews nr_files by the size of the slab array, AFAICS.
> > Since we check nr_files before we allocate files from slab, the
> > check seems inaccurate.
> > 
> > Anyway, I guess, I need to look at scaling the file counting
> > first.
> 
> Something like vm_acct_memory() or percpu_counter would suit.

Yes, that is what I am doing, except that because of the sysctl 
stuff, I now have to wallow myself in /proc code.

Thanks
Dipankar