From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 25 Jul 2007 14:06:49 +0100 Subject: Re: [PATCH] add __GFP_ZERO to GFP_LEVEL_MASK Message-ID: <20070725130649.GC32445@skynet.ie> References: <1185185020.8197.11.camel@twins> <20070723112143.GB19437@skynet.ie> <1185190711.8197.15.camel@twins> <1185256869.8197.27.camel@twins> <1185261894.8197.33.camel@twins> <20070724120751.401bcbcb@schroedinger.engr.sgi.com> <20070724122542.d4ac734a.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20070724122542.d4ac734a.akpm@linux-foundation.org> From: mel@skynet.ie (Mel Gorman) Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Christoph Lameter , Peter Zijlstra , Linus Torvalds , linux-kernel , Daniel Phillips , linux-mm List-ID: On (24/07/07 12:25), Andrew Morton didst pronounce: > On Tue, 24 Jul 2007 12:07:51 -0700 > Christoph Lameter wrote: > > > Then there are some other flags. I am wondering why they are in > > GFP_LEVEL_MASK? > > > > __GFP_COLD Does not make sense for slab allocators since we have > > to touch the page immediately. > > > > __GFP_COMP No effect. Added by the page allocator on their own > > if a higher order allocs are used for a slab. > > > > __GFP_MOVABLE The movability of a slab is determined by the > > options specified at kmem_cache_create time. If this is > > specified at kmalloc time then we will have some random > > slabs movable and others not. > > Yes, they seem inappropriate. Especially the first two. And the third one is also inappropriate by the definition of GFP_LEVEL_MASK Christoph is using. If GFP_LEVEL_MASK is to be used to filter out flags that are unsuitable for higher allocators such as slab and vmalloc, then they shouldn't be using __GFP_MOVABLE because they are unlikely to do the correct thing with the pages. When the flags were added, I was treating GFP_LEVEL_MASK as a set of allowed flags to the allocator. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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