Re: [RFC] Parallelize IO for e2fsck

["KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>]

Hi Pavel

> > > As user pages are always in highmem, this should be easy to decide:
> > > only send SIGDANGER when highmem is full. (Yes, there are
> > > inodes/dentries/file descriptors in lowmem, but I doubt apps will
> > > respond to SIGDANGER by closing files).
> >
> > Good point; for a system with at least (say) 2GB of memory, that
> > definitely makes sense.  For a system with less than 768 megs of
> > memory (how quaint, but it wasn't that long ago this was a lot of
> > memory :-), there wouldn't *be* any memory in highmem at all....
>
> Ok, so it is 'send SIGDANGER when all zones are low', because user
> allocations can go from all zones (unless you have something really
> exotic, I'm not sure if that is true on huge NUMA  machines & similar).

thank you good point out.

to be honest, the zone awareness of current mem_notify is premature.
I think we need enhancement rss statistics to per zone rss.
but not implemented yet ;-)

and, unfortunately I have no highmem machine.
the mem_notify is not so tested on highmem machine.

if you help to test, I am very happy!
Thanks.