From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 9 Nov 2004 21:34:07 -0200
From: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Subject: Re: [PATCH] kswapd shall not sleep during page shortage
Message-ID: <20041109233407.GF8414@logos.cnet>
References: <20041109164642.GE7632@logos.cnet> <20041109121945.7f35d104.akpm@osdl.org> <20041109174125.GF7632@logos.cnet> <20041109133343.0b34896d.akpm@osdl.org> <20041109182622.GA8300@logos.cnet> <20041109142257.1d1411e1.akpm@osdl.org> <20041109203143.GC8414@logos.cnet> <20041109162801.7f7ca242.akpm@osdl.org> <20041109231654.GE8414@logos.cnet>
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To: Andrew Morton <akpm@osdl.org>
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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.
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