Date: Thu, 13 Feb 2014 13:06:43 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: David Rientjes <rientjes@google.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        Fengguang Wu <fengguang.wu@intel.com>,
        David Cohen <david.a.cohen@linux.intel.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Damien Ramonda <damien.ramonda@intel.com>, Jan Kara <jack@suse.cz>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Nishanth Aravamudan <nacc@linux.vnet.ibm.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Anton Blanchard <anton@samba.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local
 memory and limit readahead pages
Message-Id: <20140213130643.0cf5fb083056cdd159d1aac4@linux-foundation.org>
In-Reply-To: <alpine.DEB.2.02.1402130003320.11689@chino.kir.corp.google.com>
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On Thu, 13 Feb 2014 00:05:31 -0800 (PST) David Rientjes <rientjes@google.com> wrote:

> On Thu, 13 Feb 2014, Raghavendra K T wrote:
> 
> > I was able to test (1) implementation on the system where readahead problem
> > occurred. Unfortunately it did not help.
> > 
> > Reason seem to be that CONFIG_HAVE_MEMORYLESS_NODES dependency of
> > numa_mem_id(). The PPC machine I am facing problem has topology like
> > this:
> > 
> > numactl -H
> > ---------
> > available: 2 nodes (0-1)
> > node 0 cpus: 0 1 2 3 4 5 6 7 12 13 14 15 16 17 18 19 20 21 22 23 24 25
> > ...
> > node 0 size: 0 MB
> > node 0 free: 0 MB
> > node 1 cpus: 8 9 10 11 32 33 34 35 ...
> > node 1 size: 8071 MB
> > node 1 free: 2479 MB
> > node distances:
> > node   0   1
> >   0:  10  20
> >   1:  20  10
> > 
> > So it seems numa_mem_id() does not help for all the configs..
> > Am I missing something ?
> > 
> 
> You need the patch from http://marc.info/?l=linux-mm&m=139093411119013 
> first.

That (un-signed-off) powerpc patch appears to be moribund.  What's up?
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