From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 4 Nov 2005 16:53:17 +0100 From: Ingo Molnar Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-ID: <20051104155317.GA7281@elte.hu> References: <20051104010021.4180A184531@thermo.lanl.gov> <20051103221037.33ae0f53.pj@sgi.com> <20051104063820.GA19505@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Paul Jackson , andy@thermo.lanl.gov, mbligh@mbligh.org, akpm@osdl.org, arjan@infradead.org, arjanv@infradead.org, haveblue@us.ibm.com, kravetz@us.ibm.com, lhms-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mel@csn.ul.ie, nickpiggin@yahoo.com.au List-ID: * Linus Torvalds wrote: > Boot-time option to set the hugetlb zone, yes. > > Grow-or-shrink, probably not. Not in practice after bootup on any > machine that is less than idle. > > The zones have to be pretty big to make any sense. You don't just grow > them or shrink them - they'd be on the order of tens of megabytes to > gigabytes. In other words, sized big enough that you will _not_ be > able to create them on demand, except perhaps right after boot. i think the current hugepages= boot option could transparently be morphed into a 'separate zone' approach, and /proc/sys/vm/nr_hugepages would just refuse to change (or would go away altogether). Dynamically growing zones seem like a lot of trouble, without much gain. [ OTOH hugepages= parameter unit should be changed from the current 'number of hugepages' to plain RAM metrics - megabytes/gigabytes. ] that would solve two problems: any 'zone VM statistics skewing effect' of the current hugetlbs (which is a preallocated list of really large pages) would go away, and the hugetlb zone could potentially be utilized for easily freeable objects. this would already be alot more flexible that what we have: the hugetlb area would not be 'lost' altogether, like now. Once we are at this stage we can see how usable it is in practice. I strongly suspect it will cover most of the HPC uses. Ingo -- 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