From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sunset.davemloft.net (unknown [74.93.104.97]) by ozlabs.org (Postfix) with ESMTP id 74FD3DDED1 for ; Thu, 26 Feb 2009 22:34:24 +1100 (EST) Date: Thu, 26 Feb 2009 03:34:06 -0800 (PST) Message-Id: <20090226.033406.60071032.davem@davemloft.net> To: anton@samba.org Subject: Re: [PATCH] Enable hashdist by default on 64bit NUMA From: David Miller In-Reply-To: <20090226112431.GA25330@kryten> References: <20090220051956.GE32195@kryten> <20090220.000354.198880712.davem@davemloft.net> <20090226112431.GA25330@kryten> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Anton Blanchard Date: Thu, 26 Feb 2009 22:24:32 +1100 > On PowerPC we allocate large boot time hashes on node 0. This leads to > an imbalance in the free memory, for example on a 64GB box (4 x 16GB > nodes): > > Free memory: > Node 0: 97.03% > Node 1: 98.54% > Node 2: 98.42% > Node 3: 98.53% > > If we switch to using vmalloc (like ia64 and x86-64) things are more > balanced: > > Free memory: > Node 0: 97.53% > Node 1: 98.35% > Node 2: 98.33% > Node 3: 98.33% > > For many HPC applications we are limited by the free available memory on > the smallest node, so even though the same amount of memory is used the > better balancing helps. > > Since all 64bit NUMA capable architectures should have sufficient > vmalloc space, it makes sense to enable it via CONFIG_64BIT. > > Signed-off-by: Anton Blanchard Acked-by: David S. Miller