Date: Wed, 26 Nov 2003 18:25:53 +1100
From: Anton Blanchard <anton@samba.org>
To: Jack Steiner <steiner@sgi.com>
Cc: Jes Sorensen <jes@trained-monkey.org>, Alexander Viro <viro@math.psu.edu>,
       Andrew Morton <akpm@osdl.org>,
       "William Lee Irwin, III" <wli@holomorphy.com>,
       linux-kernel@vger.kernel.org, jbarnes@sgi.com
Subject: Re: hash table sizes
Message-ID: <20031126072553.GF26811@krispykreme>
References: <16323.23221.835676.999857@gargle.gargle.HOWL> <20031125204814.GA19397@sgi.com> <20031125211611.GE26811@krispykreme> <20031125231108.GA5675@sgi.com>
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> That was a concern to me too. However, on IA64, all page structs are
> in the vmalloc region (it isnt allocated by vmalloc but is in the same
> region as vmalloc'ed pages. They are mapped with 16k pages instead of
> the 64MB pages used for memory allocated by kmalloc).
> 
> Before switching to 16K pages for the page structs, we made numerous
> performance measurements. As far as we could tell, there was no
> performce degradation caused by the smaller pages. It seems to me that
> if page structs are ok being mapped by 16k pages, the hash tables
> would be ok too. 

OK, on ppc64 with a 4kB base pagesize Id be more worried about using the
vmalloc region.

Anton
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