Re: [PATCH] kswapd shall not sleep during page shortage

Marcelo Tosatti
2004-11-09T23:34:07Z

On Tue, Nov 09, 2004 at 09:16:54PM -0200, Marcelo Tosatti wrote:
> On Tue, Nov 09, 2004 at 04:28:01PM -0800, Andrew Morton wrote:
> > Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
> > >
> > > Back to arguing in favour of my patch - it seemed to me that kswapd could
> > > go to sleep leaving allocators which can't reclaim pages themselves in a
> > > bad situation.
> >
> > Yes, but those processes would be sleeping in blk_congestion_wait() during,
> > say, a GFP_NOIO/GFP_NOFS allocation attempt.
>
> I was thinking about interrupts when I mentioned "allocators which can't reclaim
> pages" :)
>
> > And in that case, they may be
> > holding locks whcih prevent kswapd from being able to do any work either.
>
> OK... Just out of curiosity:
> Isnt the "lock contention" at this level (filesystem) a relatively rare situation?
>
> It could be a NFS lock for example? What other kind of lock?

Rather stupid question - filesystem internal locks like i_sem -
not NFS locks.