Date: Mon, 27 Apr 2009 10:12:26 -0400 (EDT)
From: Christoph Lameter <cl@linux.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
cc: Wu Fengguang <fengguang.wu@intel.com>,
       Balbir Singh <balbir@linux.vnet.ibm.com>,
       Badari Pulavarty <pbadari@us.ibm.com>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       Vivek Kashyap <vivk@us.ibm.com>, Mel Gorman <mel@linux.vnet.ibm.com>,
       Robert MacFarlan <Robert_MacFarlan@us.ibm.com>,
       "Fu, Michael" <michael.fu@intel.com>
Subject: Re: Large Pages - Linux Foundation HPC
In-Reply-To: <1240728861.29485.41.camel@nimitz>
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References: <1240331533.32731.2.camel@badari-desktop>  <1240333025.32604.392.camel@nimitz>  <20090421182555.GA8977@balbir.in.ibm.com>  <20090425084804.GA517@localhost> <1240728861.29485.41.camel@nimitz>
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On Sat, 25 Apr 2009, Dave Hansen wrote:

> On Sat, 2009-04-25 at 16:48 +0800, Wu Fengguang wrote:
> > Based on Dave's descriptions that HPC apps typically
> > - do mlock(), to pre-populate memory and pin them in memory
> > - run at fresh boot, with loads of high order pages available
>
> There are definitely some of them that do this, but it certainly isn't
> all.  It may not even be the norm.

Some of the machine have so much memory available that 2M allocations are
likely to succeed. If a machine has a couple of terabytes of memory
available then its highly unlikely that a 2M allocation will not succeed.

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