From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Date: Thu, 05 Apr 2007 23:10:27 +0000 Subject: Re: [PATCH 4/4] IA64: SPARSE_VIRTUAL 16M page size support Message-Id: <20070405.161027.115909479.davem@davemloft.net> List-Id: References: <20070404230635.20292.81141.sendpatchset@schroedinger.engr.sgi.com> <617E1C2C70743745A92448908E030B2A0153594A@scsmsx411.amr.corp.intel.com> In-Reply-To: <617E1C2C70743745A92448908E030B2A0153594A@scsmsx411.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: tony.luck@intel.com Cc: clameter@sgi.com, akpm@linux-foundation.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, mbligh@google.com, linux-mm@kvack.org, ak@suse.de, hansendc@us.ibm.com, kamezawa.hiroyu@jp.fujitsu.com From: "Luck, Tony" Date: Thu, 5 Apr 2007 15:50:02 -0700 > Maybe a granule is not the right unit of allocation ... perhaps 4M > would work better (4M/56 ~= 75000 pages ~= 1.1G)? But if this is > too small, then a hard-coded 16M would be better than a granule, > because 64M is (IMHO) too big. A 4MB chunk of page structs covers about 512MB of ram (I'm rounding up to 64-bytes in my calculations and using an 8K page size, sorry :-). So I think that is too small although on the sparc64 side that is the biggest I have available on most processor models. But I do agree that 64MB is way too big and 16MB is a good compromise chunk size for this stuff. That covers about 2GB of ram with the above parameters, which should be about right.