From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e2.ny.us.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id k3DHasZG013255 for ; Thu, 13 Apr 2006 13:36:54 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay04.pok.ibm.com (8.12.10/NCO/VER6.8) with ESMTP id k3DHaiWw133554 for ; Thu, 13 Apr 2006 13:36:44 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11/8.13.3) with ESMTP id k3DHahug018047 for ; Thu, 13 Apr 2006 13:36:44 -0400 Subject: [RFD hugetlbfs] strict accounting and wasteful reservations From: Adam Litke Content-Type: text/plain Date: Thu, 13 Apr 2006 12:36:42 -0500 Message-Id: <1144949802.10795.99.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: akpm@osdl.org Cc: "Chen, Kenneth W" , 'David Gibson' , wli@holomorphy.com, linux-mm@kvack.org List-ID: Sorry to bring this up after the strict accounting patch was merged but things moved along a bit too fast for me to intervene. In the thread beginning at http://lkml.org/lkml/2006/3/8/47 , a discussion was had to compare the patch from David Gibson (the patch that was ultimately merged) with an alternative patch from Ken Chen. The main functional difference is how we handle arbitrary file offsets into a hugetlb file. The current patch reserves enough huge pages to populate the whole file up to the highest file offset in use. Ken's patch supported arbitrary blocks. For libhugetlbfs, we would like to have sparsely populated hugetlb files without wasting all the extra huge pages that the current implementation requires. That aside, having yet another difference in behavior for hugetlbfs files (that isn't necessary) seems like a bad idea. So on to my questions. Do people agree that supporting reservation for sparsely populated hugetlbfs files makes sense? I've been hearing complaints about the code churn in hugetlbfs code lately, so is there a way to adapt what we currently have to support this? Otherwise, should I (or Ken?) take a stab at resurrecting Ken's competing patch with the intent of eventually replacing the current code? -- Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center -- 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