From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 23 Sep 2009 10:03:14 +1000 From: David Gibson To: Benjamin Herrenschmidt Subject: Re: powerpc: Move 64bit heap above 1TB on machines with 1TB segments Message-ID: <20090923000314.GB26739@yookeroo.seuss> References: <20090922025235.GD31801@kryten> <1253653702.7103.244.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1253653702.7103.244.camel@pasglop> Cc: linuxppc-dev@lists.ozlabs.org, Mel Gorman , Anton Blanchard List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Sep 23, 2009 at 07:08:22AM +1000, Benjamin Herrenschmidt wrote: > > > Unfortunately, I am not sensitive to issues surrounding 1TB segments or how > > they are currently being used. However, as this clearly helps performance > > for large amounts of memory, is it worth providing an option to > > libhugetlbfs to locate 16MB pages above 1TB when they are otherwise being > > unused? > > AFAIK, that is already the case, at least the kernel will hand out pages > above 1T preferentially iirc. > > There were talks about making huge pages below 1T not even come up > untily you ask for them with MAP_FIXED, dunno where that went. That was already the case as far as I remember. But it's just possible that changed when the general slice handling code came in, -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson