From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate4.de.ibm.com (8.13.8/8.13.8) with ESMTP id l9Q88L83057904 for ; Fri, 26 Oct 2007 08:08:21 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l9Q88LO01822970 for ; Fri, 26 Oct 2007 10:08:21 +0200 Received: from d12av02.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l9Q88K27023536 for ; Fri, 26 Oct 2007 10:08:21 +0200 Subject: Re: [patch 2/6] CONFIG_HIGHPTE vs. sub-page page tables. From: Martin Schwidefsky Reply-To: schwidefsky@de.ibm.com In-Reply-To: <1193385617.13638.3.camel@pasglop> References: <20071025181520.880272069@de.ibm.com> <20071025181901.212545095@de.ibm.com> <1193345221.7018.18.camel@pasglop> <1193384578.31831.6.camel@localhost> <1193385617.13638.3.camel@pasglop> Content-Type: text/plain Date: Fri, 26 Oct 2007 10:08:20 +0200 Message-Id: <1193386100.31831.13.camel@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: benh@kernel.crashing.org Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com List-ID: On Fri, 2007-10-26 at 18:00 +1000, Benjamin Herrenschmidt wrote: > > > Interesting. That means I don't need to have a PTE page to be a struct > > > page anymore ? I can have good use for that on powerpc as well... > > > > That would be good news. I'm curious, can you elaborate on what the use > > case is? > > When using 64K pages, we use 32K of PTEs and 32K of "extension". The > extension thing is used when using HW 4K pages, to keep track of the > subpages. On setups where that isn't needed, we can save memory by > allocating half pages... Ahh, that is exactly the same reason as for s390. Page tables with a size that is sub-page. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org